query: What is the pH scale?

title: PH

text: cause changes in electrode potential. To resolve this problem, an alternative series of buffers based on artificial seawater was developed. This new series resolves the problem of ionic strength differences between samples and the buffers, and the new pH scale is referred to as the 'total scale', often denoted as pH. The total scale was defined using a medium containing sulfate ions. These ions experience protonation, H + SO HSO, such that the total scale includes the effect of both protons (free hydrogen ions) and hydrogen sulfate ions: An alternative scale, the 'free scale', often denoted 'pH', omits this consideration

title: PH

text: the Hammett acidity function, "H", has been developed in connection with superacids. The concept of "unified pH scale" has been developed on the basis of the absolute chemical potential of the proton. This model uses the Lewis acid–base definition. This scale applies to liquids, gases and even solids. In 2010, a new "unified absolute pH scale" has been proposed that would allow various pH ranges across different solutions to use a common proton reference standard. Pure water is neutral. When an acid is dissolved in water, the pH will be less than 7 (25 °C). When a base, or alkali,

title: PH

text: is dissolved in water, the pH will be greater than 7. A solution of a strong acid, such as hydrochloric acid, at concentration 1 mol dm has a pH of 0. A solution of a strong alkali, such as sodium hydroxide, at concentration 1 mol dm, has a pH of 14. Thus, measured pH values will lie mostly in the range 0 to 14, though negative pH values and values above 14 are entirely possible. Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration. <br> The pH

title: PH

text: temperature increases. Pure water is neutral, pH 7 at (25 °C), being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively. Measurements of pH are important in agronomy, medicine, chemistry, water treatment, and many other applications. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such

title: PH

text: PH In chemistry, pH () is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. The neutral value of the pH depends on the temperature, being lower than 7 if the

title: PH

text: cycle, and there is evidence of ongoing ocean acidification caused by carbon dioxide emissions. However, pH measurement is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography. As part of its operational definition of the pH scale, the IUPAC defines a series of buffer solutions across a range of pH values (often denoted with NBS or NIST designation). These solutions have a relatively low ionic strength (≈0.1) compared to that of seawater (≈0.7), and, as a consequence, are not recommended for use in characterizing the pH of seawater, since the ionic strength differences

title: PH

text: that liquid junction potentials are independent of pH. Also, extreme pH implies that the solution is concentrated, so electrode potentials are affected by ionic strength variation. At high pH the glass electrode may be affected by "alkaline error", because the electrode becomes sensitive to the concentration of cations such as Na and K in the solution. Specially constructed electrodes are available which partly overcome these problems. Runoff from mines or mine tailings can produce some very low pH values. Hydrogen ion concentrations (activities) can be measured in non-aqueous solvents. pH values based on these measurements belong to a different scale

title: PH indicator

text: red, both species confer a color. While pH indicators work efficiently at their designated pH range, they are usually destroyed at the extreme ends of the pH scale due to undesired side reactions. pH indicators are frequently employed in titrations in analytical chemistry and biology to determine the extent of a chemical reaction. Because of the subjective choice (determination) of color, pH indicators are susceptible to imprecise readings. For applications requiring precise measurement of pH, a pH meter is frequently used. Sometimes, a blend of different indicators is used to achieve several smooth color changes over a wide range of

title: PH

text: from aqueous pH values, because activities relate to different standard states. Hydrogen ion activity, "a", can be defined as: where "μ" is the chemical potential of the hydrogen ion, formula_9 is its chemical potential in the chosen standard state, "R" is the gas constant and "T" is the thermodynamic temperature. Therefore, pH values on the different scales cannot be compared directly due to different solvated proton ions such as lyonium ions, requiring an intersolvent scale which involves the transfer activity coefficient of hydronium/lyonium ion. pH is an example of an acidity function. Other acidity functions can be defined. For example,

title: PH

text: to a straight line with respect to standard buffer values. Commercial standard buffer solutions usually come with information on the value at 25 °C and a correction factor to be applied for other temperatures. The pH scale is logarithmic and therefore pH is a dimensionless quantity. This was the original definition of Sørensen, which was superseded in favor of pH in 1909. However, it is possible to measure the concentration of hydrogen ions directly, if the electrode is calibrated in terms of hydrogen ion concentrations. One way to do this, which has been used extensively, is to titrate a solution

title: PH

text: than three reagents. The calculation of hydrogen ion concentrations, using this formalism, is a key element in the determination of equilibrium constants by potentiometric titration. PH In chemistry, pH () is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and

title: Fecal pH test

text: milliliter of feces is collected and a strip of nitrazine paper is dipped in the sample and compared against a color scale. A pH of less than 5.5 indicates an acidic sample. Unhealthy individuals with a higher or lower pH rate have been observed having a higher mortality rate. A high alkaline pH rating being associated with the body's inability to create enough acid along with undigested food. Fecal pH test A fecal pH test is one where a specimen of feces is tested for acidity in order to diagnose a medical condition. Human feces is normally acidic. An acidic

title: PH

text: and focuses solely on [H], in principle making it a simpler representation of hydrogen ion concentration. Only [H] can be determined, therefore [H] must be estimated using the [SO] and the stability constant of HSO, : However, it is difficult to estimate K in seawater, limiting the utility of the otherwise more straightforward free scale. Another scale, known as the 'seawater scale', often denoted 'pH', takes account of a further protonation relationship between hydrogen ions and fluoride ions, H + F ⇌ HF. Resulting in the following expression for [H]: However, the advantage of considering this additional complexity is dependent

title: PH meter

text: to be set. Standard buffer sachets, available from a variety of suppliers, usually document the temperature dependence of the buffer control. More precise measurements sometimes require calibration at three different pH values. Some pH meters provide built-in temperature-coefficient correction, with temperature thermocouples in the electrode probes. The calibration process correlates the voltage produced by the probe (approximately 0.06 volts per pH unit) with the pH scale. Good laboratory practice dictates that, after each measurement, the probes are rinsed with distilled water or deionized water to remove any traces of the solution being measured, blotted with a scientific wipe to absorb

title: PH

text: the concentration of the acid, so [A] = [H]. After some further algebraic manipulation an equation in the hydrogen ion concentration may be obtained. Solution of this quadratic equation gives the hydrogen ion concentration and hence p[H] or, more loosely, pH. This procedure is illustrated in an ICE table which can also be used to calculate the pH when some additional (strong) acid or alkaline has been added to the system, that is, when C ≠ C. For example, what is the pH of a 0.01M solution of benzoic acid, pK = 4.19? For alkaline solutions an additional term is

title: PH

text: a standard color chart provides a means to measure pH accurate to the nearest whole number. More precise measurements are possible if the color is measured spectrophotometrically, using a colorimeter or spectrophotometer. Universal indicator consists of a mixture of indicators such that there is a continuous color change from about pH 2 to pH 10. Universal indicator paper is made from absorbent paper that has been impregnated with universal indicator. Another method of measuring pH is using an electronic pH meter. pOH is sometimes used as a measure of the concentration of hydroxide ions. OH. pOH values are derived from

title: PH meter

text: PH meter A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a "potentiometric pH meter". The difference in electrical potential relates to the acidity or pH of the solution. The pH meter is used in many applications ranging from laboratory experimentation to quality control. The rate and outcome of chemical reactions taking place in water often depends on the

title: PH

text: used as pH indicators occur in many plants, including hibiscus, red cabbage (anthocyanin) and red wine. The juice of citrus fruits is acidic mainly because it contains citric acid. Other carboxylic acids occur in many living systems. For example, lactic acid is produced by muscle activity. The state of protonation of phosphate derivatives, such as ATP, is pH-dependent. The functioning of the oxygen-transport enzyme hemoglobin is affected by pH in a process known as the Root effect. The pH of seawater is typically limited to a range between 7.5 and 8.4. It plays an important role in the ocean's carbon

title: Soil pH

text: Soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions ( or, more precisely, ) in a solution. In soils, it is measured in a slurry of soil mixed with water (or a salt solution, such as 0.01 M ), and normally falls between 3 and 10, with 7 being neutral. Acid soils have a pH below 7 and alkaline soils have a pH above 7. Ultra-acidic soils (pH < 3.5) and very strongly alkaline soils (pH > 9)

title: PH

text: pH 7.365. This value is often referred to as physiological pH in biology and medicine. Plaque can create a local acidic environment that can result in tooth decay by demineralization. Enzymes and other proteins have an optimum pH range and can become inactivated or denatured outside this range. The calculation of the pH of a solution containing acids and/or bases is an example of a chemical speciation calculation, that is, a mathematical procedure for calculating the concentrations of all chemical species that are present in the solution. The complexity of the procedure depends on the nature of the solution. For

title: Soil pH

text: Because roots are damaged, nutrient uptake is reduced, and deficiencies of the macronutrients (nitrogen, phosphorus, potassium, calcium and magnesium) are frequently encountered in very strongly acidic to ultra-acidic soils (pH<5.0). Molybdenum availability is increased at higher pH; this is because the molybdate ion is more strongly sorbed by clay particles at lower pH. Zinc, iron, copper and manganese show decreased availability at higher pH (increased sorbtion at higher pH). The effect of pH on phosphorus availability varies considerably, depending on soil conditions and the crop in question. The prevailing view in the 1940s and 1950s was that P availability was

title: Intracellular pH

text: Intracellular pH Intracellular pH (pHi) is the measure of the acidity or basicity (i.e., pH) of intracellular fluid. The pHi plays a critical role in membrane transport and other intracellular processes. The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those that are dependent and those that are independent of HCO. Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pHi of 6.8-7.1). Intracellular pH is typically lower than extracellular pH due to

title: PH indicator

text: PH indicator A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (HO) or hydrogen ions (H) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a

title: Intracellular pH

text: lower concentrations of HCO . When extracellular (e.g., serum) pCO levels rise above 45 mmHg, the cell will uptake more H to buffer, and pHi decreases. Lymphocytes maintain a constant internal pH of 7.17± 0.06, though, like all cells, the intracellular pH changes in the same direction as extracellular pH. Pioneer researchers in the area of intracellular pH include Jacques Pouyssegur (University of Nice, France), Albrecht Schwab, University of Münster, Germany, and Diane Barber, University of California, San Francisco, USA. Intracellular pH Intracellular pH (pHi) is the measure of the acidity or basicity (i.e., pH) of intracellular fluid. The pHi

title: PH indicator

text: pH values. These commercial indicators (e.g., universal indicator and Hydrion papers) are used when only rough knowledge of pH is necessary. Tabulated below are several common laboratory pH indicators. Indicators usually exhibit intermediate colors at pH values inside the listed transition range. For example, phenol red exhibits an orange color between pH 6.8 and pH 8.4. The transition range may shift slightly depending on the concentration of the indicator in the solution and on the temperature at which it is used. The figure on the right shows indicators with their operation range and color changes. An indicator may be used

title: PH meter

text: first portable digital pH meter. This meter was sold under the label of the Cole-Parmer Corporation. Specialized manufacturing is required for the electrodes, and details of their design and construction are typically trade secrets. However, with purchase of suitable electrodes, a standard multimeter can be used to complete the construction of the pH meter. However, commercial suppliers offer voltmeter displays that simplify use, including calibration and temperature compensation. PH meter A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. The pH meter measures the difference in

title: PH

text: upon the abundance of fluoride in the medium. In seawater, for instance, sulfate ions occur at much greater concentrations (>400 times) than those of fluoride. As a consequence, for most practical purposes, the difference between the total and seawater scales is very small. The following three equations summarise the three scales of pH: In practical terms, the three seawater pH scales differ in their values by up to 0.12 pH units, differences that are much larger than the accuracy of pH measurements typically required, in particular, in relation to the ocean's carbonate system. Since it omits consideration of sulfate and

title: Soil pH

text: maximized near neutrality (soil pH 6.5–7.5), and decreased at higher and lower pH. Interactions of phosphorus with pH in the moderately to slightly acidic range (pH 5.5–6.5) are, however, far more complex than is suggested by this view. Laboratory tests, glasshouse trials and field trials have indicated that increases in pH within this range may increase, decrease, or have no effect on P availability to plants. Strongly alkaline soils are sodic and dispersive, with slow infiltration, low hydraulic conductivity and poor available water capacity. Plant growth is severely restricted because aeration is poor when the soil is wet; in dry

title: Soil pH

text: sphagnum peat moss. However, in high-pH soils with a high calcium carbonate content (more than 2%), it can be very costly and/or ineffective to attempt to reduce the pH with acids. In such cases, it is often more efficient to add phosphorus, iron, manganese, copper and/or zinc instead, because deficiencies of these nutrients are the most common reasons for poor plant growth in calcareous soils. Soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions ( or, more precisely,

title: PH

text: represents the concentration of the hydroxide ion. This equilibrium needs to be taken into account at high pH and when the solute concentration is extremely low. Strong acids and bases are compounds that, for practical purposes, are completely dissociated in water. Under normal circumstances this means that the concentration of hydrogen ions in acidic solution can be taken to be equal to the concentration of the acid. The pH is then equal to minus the logarithm of the concentration value. Hydrochloric acid (HCl) is an example of a strong acid. The pH of a 0.01M solution of HCl is equal

title: PH

text: of both ions. However the pH of the neutral NaCl solution will be slightly different from that of neutral pure water because the hydrogen and hydroxide ions' activity is dependent on ionic strength, so K varies with ionic strength. If pure water is exposed to air it becomes mildly acidic. This is because water absorbs carbon dioxide from the air, which is then slowly converted into bicarbonate and hydrogen ions (essentially creating carbonic acid). The United States Department of Agriculture Natural Resources Conservation Service, formerly Soil Conservation Service classifies soil pH ranges as follows: pH-dependent plant pigments that can be

title: PH

text: a pH of 7.3. This is clearly wrong as an acid solution should have a pH of less than 7. Treating the system as a mixture of hydrochloric acid and the amphoteric substance water, a pH of 6.89 results. A weak acid or the conjugate acid of a weak base can be treated using the same formalism. First, an acid dissociation constant is defined as follows. Electrical charges are omitted from subsequent equations for the sake of generality and its value is assumed to have been determined by experiment. This being so, there are three unknown concentrations, [HA], [H] and

title: PH

text: pH measurements. The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by where "K" is the self-ionisation constant of water. Taking logarithms So, at room temperature, pOH ≈ 14 − pH. However this relationship is not strictly valid in other circumstances, such as in measurements of soil alkalinity. Measurement of pH below about 2.5 (ca. 0.003 mol dm acid) and above about 10.5 (ca. 0.0003 mol dm alkaline) requires special procedures because, when using the glass electrode, the Nernst law breaks down under those conditions. Various factors contribute to this. It cannot be assumed

title: PH

text: which they came into wide usage. The first electronic method for measuring pH was invented by Arnold Orville Beckman, a professor at California Institute of Technology in 1934. It was in response to local citrus grower Sunkist that wanted a better method for quickly testing the pH of lemons they were picking from their nearby orchards. pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, "a"+, in a solution. For example, for a solution with a hydrogen ion activity of (at that level, this is essentially the number of moles of hydrogen ions per

title: PH indicator

text: pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic (alkaline). As most naturally occurring organic compounds are weak protolytes, carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred, whereas the third compound class, the redox indicators, are used in titrations involving a redox reaction as the basis of the analysis. In and of themselves, pH indicators are

title: Immobilized pH gradient

text: gradient instability and poor sample loading capacity associated with carrier ampholyte pH gradient. Commercial precast IPG gels are available. Immobilized pH gradient Immobilized pH gradient (IPG) gels are the acrylamide gel matrix co-polymerized with the pH gradient, which result in completely stable gradients except the most alkaline (>12) pH values. The immobilized pH gradient is obtained by the continuous change in the ratio of "Immobilines". An "Immobiline" is a weak acid or base defined by its pK value. Immobilized pH gradients (IPG) are made by mixing two kinds of acrylamide mixture, one with Immobiline having acidic buffering property and other

title: PH indicator

text: frequently weak acids or weak bases. The general reaction scheme of a pH indicator can be formulated as: Here, HInd stands for the acid form and Ind for the conjugate base of the indicator. The ratio of these determines the color of the solution and connects the color to the pH value. pH indicators that are weak protolytes, the Henderson–Hasselbalch equation for them can be written as: The equation, derived from the acidity constant, states that when pH equals the p"K" value of the indicator, both species are present in a 1:1 ratio. If pH is above the p"K" value,

title: PH-sensitive polymers

text: can be used to release of insulin. PH-sensitive polymers pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Materials may swell, collapse, or change depending on the pH of their environment. This behavior is exhibited due to the presence of certain functional groups in the polymer chain. pH-sensitive materials can be either acidic or basic, responding to either basic or acidic pH values. These polymers can be designed with many different architectures for different applications. Key uses of pH sensitive polymers are controlled drug

title: PH-sensitive polymers

text: PH-sensitive polymers pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Materials may swell, collapse, or change depending on the pH of their environment. This behavior is exhibited due to the presence of certain functional groups in the polymer chain. pH-sensitive materials can be either acidic or basic, responding to either basic or acidic pH values. These polymers can be designed with many different architectures for different applications. Key uses of pH sensitive polymers are controlled drug delivery systems, biomimetics, micromechanical systems, separation processes,

title: PH indicator

text: reactions occur in the soil that make aluminium available to these plants, turning the flowers blue. In alkaline soils, these reactions cannot occur and therefore aluminium is not taken up by the plant. As a result, the flowers remain pink. PH indicator A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (HO) or hydrogen ions (H) in the Arrhenius model. Normally, the indicator causes the color of the solution to

title: PH meter

text: acidity of the water, and it is therefore useful to know the acidity of the water, typically measured by means of a pH meter. Knowledge of pH is useful or critical in many situations, including chemical laboratory analyses. pH meters are used for soil measurements in agriculture, water quality for municipal water supplies, swimming pools, environmental remediation; brewing of wine or beer; manufacturing, healthcare and clinical applications such as blood chemistry; and many other applications. Advances in the instrumentation and in detection have expanded the number of applications in which pH measurements can be conducted. The devices have been miniaturized,

title: Immobilized pH gradient

text: Immobilized pH gradient Immobilized pH gradient (IPG) gels are the acrylamide gel matrix co-polymerized with the pH gradient, which result in completely stable gradients except the most alkaline (>12) pH values. The immobilized pH gradient is obtained by the continuous change in the ratio of "Immobilines". An "Immobiline" is a weak acid or base defined by its pK value. Immobilized pH gradients (IPG) are made by mixing two kinds of acrylamide mixture, one with Immobiline having acidic buffering property and other with basic buffering property. The concentrations of the buffers in the two solutions define the range and shape of

title: PH indicator

text: the concentration of the conjugate base is 10 times greater than the concentration of the acid, their ratio is 10:1, and consequently the pH is p"K" + 1. Conversely, if a 10-fold excess of the acid occurs with respect to the base, the ratio is 1:10 and the pH is p"K" − 1. For optimal accuracy, the color difference between the two species should be as clear as possible, and the narrower the pH range of the color change the better. In some indicators, such as phenolphthalein, one of the species is colorless, whereas in other indicators, such as methyl

title: PH indicator

text: the concentration of the conjugate base is greater than the concentration of the acid, and the color associated with the conjugate base dominates. If pH is below the p"K" value, the converse is true. Usually, the color change is not instantaneous at the p"K" value, but a pH range exists where a mixture of colors is present. This pH range varies between indicators, but as a rule of thumb, it falls between the p"K" value plus or minus one. This assumes that solutions retain their color as long as at least 10% of the other species persists. For example, if

title: Soil pH

text: a very wide pH range. Finely ground agricultural lime is often applied to acid soils to increase soil pH (liming). The amount of limestone or chalk needed to change pH is determined by the mesh size of the lime (how finely it is ground) and the buffering capacity of the soil. A high mesh size (60 mesh = 0.25 mm; 100 mesh = 0.149 mm) indicates a finely ground lime that will react quickly with soil acidity. The buffering capacity of a soil depends on the clay content of the soil, the type of clay, and the amount of organic

title: PH indicator

text: range p"K" ± 1, but this range can be extended by using mixtures of two or more indicators. Because indicators have intense absorption spectra, the indicator concentration is relatively low, and the indicator itself is assumed to have a negligible effect on pH. In acid-base titrations, an unfitting pH indicator may induce a color change in the indicator-containing solution before or after the actual equivalence point. As a result, different equivalence points for a solution can be concluded based on the pH indicator used. This is because the slightest color change of the indicator-containing solution suggests the equivalence point has

title: Fecal pH test

text: Fecal pH test A fecal pH test is one where a specimen of feces is tested for acidity in order to diagnose a medical condition. Human feces is normally acidic. An acidic stool can indicate a digestive problem such as lactose intolerance or a contagion such as "E. coli" or rotavirus, or overgrowth of the acid producing bacteria (such as lactic acid bacteria for instance). The average pH for a healthy person is a pH of 6.6. The test is fast and can be performed in a doctor's office. A patient must not be receiving antibiotics. At least half a

title: PH meter

text: voltage varies from test solution to test solution depending on the potential difference created by the difference in hydrogen-ion concentrations on each side of the glass membrane between the test solution and the solution inside the glass electrode. All other potential differences in the circuit do not vary with pH and are corrected for by means of the calibration. For simplicity, many pH meters use a combination probe, constructed with the glass electrode and the reference electrode contained within a single probe. A detailed description of combination electrodes is given in the article on glass electrodes. The pH meter is

title: PH

text: liter of solution) we get , thus such a solution has a pH of . For a commonplace example based on the facts that the masses of a mole of water, a mole of hydrogen ions, and a mole of hydroxide ions are respectively 18 g, 1 g, and 17 g, a quantity of 10 moles of pure (pH 7) water, or 180 tonnes (18×10 g), contains close to 1 g of dissociated hydrogen ions (or rather 19 g of HO hydronium ions) and 17 g of hydroxide ions. Note that pH depends on temperature. For instance at 0 °C

title: PH

text: of neutrality is not exactly 7 (25 °C), although this is a good approximation in most cases. Neutrality is defined as the condition where [H] = [OH] (or the activities are equal). Since self-ionization of water holds the product of these concentration [H]×[OH] = K, it can be seen that at neutrality [H] = [OH] = , or pH = pK/2. pK is approximately 14 but depends on ionic strength and temperature, and so the pH of neutrality does also. Pure water and a solution of NaCl in pure water are both neutral, since dissociation of water produces equal numbers

title: PH

text: to −log(0.01), that is, pH = 2. Sodium hydroxide, NaOH, is an example of a strong base. The p[OH] value of a 0.01M solution of NaOH is equal to −log(0.01), that is, p[OH] = 2. From the definition of p[OH] above, this means that the pH is equal to about 12. For solutions of sodium hydroxide at higher concentrations the self-ionization equilibrium must be taken into account. Self-ionization must also be considered when concentrations are extremely low. Consider, for example, a solution of hydrochloric acid at a concentration of 5×10M. The simple procedure given above would suggest that it has

title: PH

text: strong acids and bases no calculations are necessary except in extreme situations. The pH of a solution containing a weak acid requires the solution of a quadratic equation. The pH of a solution containing a weak base may require the solution of a cubic equation. The general case requires the solution of a set of non-linear simultaneous equations. A complicating factor is that water itself is a weak acid and a weak base (see amphoterism). It dissociates according to the equilibrium with a dissociation constant, defined as where [H] stands for the concentration of the aqueous hydronium ion and [OH]

title: PH indicator

text: been reached. Therefore, the most suitable pH indicator has an effective pH range, where the change in color is apparent, that encompasses the pH of the equivalence point of the solution being titrated. Many plants or plant parts contain chemicals from the naturally colored anthocyanin family of compounds. They are red in acidic solutions and blue in basic. Anthocyanins can be extracted with water or other solvents from a multitude of colored plants or plant parts, including from leaves (red cabbage); flowers (geranium, poppy, or rose petals); berries (blueberries, blackcurrant); and stems (rhubarb). Extracting anthocyanins from household plants, especially red

title: Soil pH

text: confounding factor is that different varieties of the same species often have different suitable soil pH ranges. Plant breeders can use this to breed varieties that can tolerate conditions that are otherwise considered unsuitable for that species – examples are projects to breed aluminium-tolerant and manganese-tolerant varieties of cereal crops for food production in strongly acidic soils. The table below gives suitable soil pH ranges for some widely cultivated plants as found in the "USDA PLANTS Database". Some species (like "Pinus radiata" and "Opuntia ficus-indica") tolerate only a narrow range in soil pH, whereas others (such as "Vetiveria zizanioides") tolerate

title: PH meter

text: calibrated with solutions of known pH, typically before each use, to ensure accuracy of measurement. To measure the pH of a solution, the electrodes are used as probes, which are dipped into the test solutions and held there sufficiently long for the hydrogen ions in the test solution to equilibrate with the ions on the surface of the bulb on the glass electrode. This equilibration provides a stable pH measurement. Details of the fabrication and resulting microstructure of the glass membrane of the pH electrode are maintained as trade secrets by the manufacturers. However, certain aspects of design are published.

title: Soil pH

text: soil. The soil pH usually increases when the total alkalinity increases, but the balance of the added cations also has a marked effect on the soil pH. For example, increasing the amount of sodium in an alkaline soil tends to induce dissolution of calcium carbonate, which increases the pH. Calcareous soils may vary in pH from 7.0 to 9.5, depending on the degree to which or dominate the soluble cations. Plants grown in acid soils can experience a variety of stresses including aluminium (Al), hydrogen (H), and/or manganese (Mn) toxicity, as well as nutrient deficiencies of calcium (Ca) and magnesium

title: PH

text: fluoride ions, the free scale is significantly different from both the total and seawater scales. Because of the relative unimportance of the fluoride ion, the total and seawater scales differ only very slightly. The pH of different cellular compartments, body fluids, and organs is usually tightly regulated in a process called acid-base homeostasis. The most common disorder in acid-base homeostasis is acidosis, which means an acid overload in the body, generally defined by pH falling below 7.35. Alkalosis is the opposite condition, with blood pH being excessively high. The pH of blood is usually slightly basic with a value of

title: .ph

text: .ph .ph is the Internet country code top-level domain (ccTLD) for the Philippines. The official domain registry of the .ph domain is dotPH Domains Inc. dotPH holds and maintains the database of PH domain names, specifically .ph, .com.ph, .net.ph, and .org.ph. Its domain name registrars are not only individuals, businesses, and organizations in the Philippines, but also those in other parts of the world. The PH domain is currently administered by José Emmanuel "Joel" Disini, who is also dotPH's current CEO. Disini has been the domain administrator since Jon Postel assigned him the domain in 1990. The domain is sponsored

title: PH

text: a medium similar to the one being investigated. For instance, if one wishes to measure the pH of a seawater sample, the electrode should be calibrated in a solution resembling seawater in its chemical composition, as detailed below. The difference between p[H] and pH is quite small. It has been stated that pH = p[H] + 0.04. It is common practice to use the term "pH" for both types of measurement. Indicators may be used to measure pH, by making use of the fact that their color changes with pH. Visual comparison of the color of a test solution with

title: RNase PH

text: RNase PH RNase PH is a 3'-5' exoribonuclease and nucleotidyltransferase, present in archaea and bacteria, that is involved in tRNA processing. Contrary to hydrolytic enzymes, it is a phosphorolytic enzyme, meaning that it uses inorganic phosphate as a reactant to cleave nucleotide-nucleotide bonds, releasing diphosphate nucleotides. The active structure of the proteins is a homohexameric complex, consisting of three ribonuclease (RNase) PH dimers. RNase PH has homologues in many other organisms, which are referred to as RNase PH-like proteins. The part of another larger protein with a domain that is very similar to RNase PH is called an RNase PH

title: PH

text: the pH of pure water is 7.47. At 25 °C it's 7.00, and at 100 °C it's 6.14. This definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. Ideally, electrode potential, "E", follows the Nernst equation, which, for the hydrogen ion can be written as where "E" is a measured potential, "E" is the standard electrode potential, "R" is the gas constant, "T" is the temperature in kelvins, "F" is the Faraday constant. For H number of electrons transferred is one. It follows that electrode potential is proportional to pH when pH is defined

title: Logarithmic scale

text: Logarithmic scale A logarithmic scale is a nonlinear scale used when there is a large range of quantities. Common uses include earthquake strength, sound loudness, light intensity, and pH of solutions. It is based on orders of magnitude, rather than a standard linear scale, so the value represented by each equidistant mark on the scale is the value at the previous mark multiplied by a constant. Logarithmic scales are also used in slide rules for multiplying or dividing numbers by adding or subtracting lengths on the scales. The following are examples of commonly used logarithmic scales, where a larger quantity

title: PH Artichoke

text: A circuit and breaker. The English name is PH Artichoke ("artichoke"). The original Danish name is "PH Kogle" ("conifer cone") This name is also used in Norway and Germany /"PH Kogle/PH Zapfen". PH Artichoke The PH Artichoke Pendant is a Light fixture designed by Danish architect and designer Poul Henningsen and manufactured by Louis Poulsen. It was created for the Langelinie Pavilion in Copenhagen in 1958. A chrome inner diffuser also assists in the proper even reflection of the light source. The light source can be an incandescent bulb (high powered halogen or xenon), fluorescent (with the ballast mounted in

title: PH (complexity)

text: PSPACE; in particular, it contains P, NP, and co-NP. It even contains probabilistic classes such as BPP and RP. However, there is some evidence that BQP, the class of problems solvable in polynomial time by a quantum computer, is not contained in PH. P = NP if and only if P = PH. This may simplify a potential proof of P ≠ NP, since it is only necessary to separate P from the more general class PH. PH (complexity) In computational complexity theory, the complexity class PH is the union of all complexity classes in the polynomial hierarchy: PH was

title: Soil pH

text: are rare. Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo. The optimum pH range for most plants is between 5.5 and 7.5; however, many plants have adapted to thrive at pH values outside this range. The United States Department of Agriculture Natural Resources Conservation Service classifies soil pH ranges as follows: Methods of determining pH include: Precise, repeatable measures of soil pH are required for scientific research and monitoring. This generally

title: What Is the What

text: What Is the What What Is the What: The Autobiography of Valentino Achak Deng is a 2006 novel written by Dave Eggers. It is based on the life of Valentino Achak Deng, a Sudanese child refugee who immigrated to the United States under the Lost Boys of Sudan program. It was a finalist for the National Book Award. As a boy, Achak is separated from his family during the Second Sudanese Civil War when the Arab militia, referred to as "murahaleen" (which is Arabic for the deported), wipes out his Dinka village, Marial Bai. During the assault, he loses sight

title: What Is the What

text: That Happens Will Happen Today". Tom Tykwer plans to adapt the novel into a film. In 2009, the novel received the Prix Médicis étranger in France. What Is the What What Is the What: The Autobiography of Valentino Achak Deng is a 2006 novel written by Dave Eggers. It is based on the life of Valentino Achak Deng, a Sudanese child refugee who immigrated to the United States under the Lost Boys of Sudan program. It was a finalist for the National Book Award. As a boy, Achak is separated from his family during the Second Sudanese Civil War when

title: RNase PH

text: domain (RPD). Two highly related exoribonuclease complexes: RNase PH RNase PH is a 3'-5' exoribonuclease and nucleotidyltransferase, present in archaea and bacteria, that is involved in tRNA processing. Contrary to hydrolytic enzymes, it is a phosphorolytic enzyme, meaning that it uses inorganic phosphate as a reactant to cleave nucleotide-nucleotide bonds, releasing diphosphate nucleotides. The active structure of the proteins is a homohexameric complex, consisting of three ribonuclease (RNase) PH dimers. RNase PH has homologues in many other organisms, which are referred to as RNase PH-like proteins. The part of another larger protein with a domain that is very similar to

title: PH (complexity)

text: PH (complexity) In computational complexity theory, the complexity class PH is the union of all complexity classes in the polynomial hierarchy: PH was first defined by Larry Stockmeyer. It is a special case of hierarchy of bounded alternating Turing machine. It is contained in P = P (by Toda's theorem; the class of problems that are decidable by a polynomial time Turing machine with access to a #P or equivalently PP oracle), and also in PSPACE. PH has a simple logical characterization: it is the set of languages expressible by second-order logic. PH contains almost all well-known complexity classes inside

title: Dentyl pH

text: Dentyl pH Dentyl Active originally known as Dentyl pH is a brand of mouthwash, an oral hygiene product designed to reduce the presence of bacteria responsible for tooth decay, gingivitis and halitosis. Traditional mouthwash formulations use alcohol or other antimicrobial ingredients to kill bacteria. Although Dentyl pH contains anti-bacterial agents (cetylpyridinium chloride, triclosan), it is atypical in that it also contains isopropyl myristate, an oily, non-aqueous, component that adheres to bacteria making them easier to rinse from the mouth. As of 2007, Dentyl pH was one of the top two mouthwash brands in the United Kingdom. Dentyl pH is sold

title: PH

text: as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. There are three current theories used to describe acid–base reactions: Arrhenius, Bronsted-Lowry and Lewis when determining pH. The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", as so: p. The

title: PH

text: more buffer solutions are used in order to accommodate the fact that the "slope" may differ slightly from ideal. To implement this approach to calibration, the electrode is first immersed in a standard solution and the reading on a pH meter is adjusted to be equal to the standard buffer's value. The reading from a second standard buffer solution is then adjusted, using the "slope" control, to be equal to the pH for that solution. Further details, are given in the IUPAC recommendations. When more than two buffer solutions are used the electrode is calibrated by fitting observed pH values

title: PH meter

text: enabling direct measurement of pH inside of living cells. In addition to measuring the pH of liquids, specially designed electrodes are available to measure the pH of semi-solid substances, such as foods. These have tips suitable for piercing semi-solids, have electrode materials compatible with ingredients in food, and are resistant to clogging. pH meters ( which is also called POTENTIOMETRIC ) measure the voltage between two electrodes and display the result converted into the corresponding pH value. They comprise a simple electronic amplifier and a pair of electrodes, or alternatively a combination electrode, and some form of display calibrated in

title: Soil pH

text: look up the suitable soil pH range of a wide range of plants. Documents like "Ellenberg's indicator values for British plants" can also be consulted. However, a plant may be intolerant of a particular pH in some soils as a result of a particular mechanism, and that mechanism may not apply in other soils. For example, a soil low in molybdenum may not be suitable for soybean plants at pH 5.5, but soils with sufficient molybdenum allow optimal growth at that pH. Similarly, some calcifuges (plants intolerant of high-pH soils) can tolerate calcareous soils if sufficient phosphorus is supplied. Another

title: PH meter

text: are available for use in special applications, such as harsh environments and biological microenvironments. There are also holographic pH sensors, which allow pH measurement colorimetrically, making use of the variety of pH indicators that are available. Additionally, there are commercially available pH meters based on solid state electrodes, rather than conventional glass electrodes. The concept of pH was defined in 1909 by S. P. L. Sørensen, and electrodes were used for pH measurement in the 1920s. In October 1934 Arnold Orville Beckman registered the first patent for a complete chemical instrument for the measurement of pH, U.S. Patent No. 2,058,761,

title: Ph as in Phony

text: possible that the student gave the teacher the questions – not vice versa – and that Faron had written the test based on what he had observed his fellow students struggling with. In other words, Faron wrote the examination paper himself and bribed his professor to use it. Ph as in Phony Ph as in Phony is a mystery written by Isaac Asimov in 1972. It was first published in the July 1972 issue of "Ellery Queen's Mystery Magazine" under the title "The Phony Ph.D." The reason for this title change was that the magazine ran a series by Lawrence

title: PH meter

text: Calibration is needed because the glass electrode does not give reproducible electrostatic potentials over longer periods of time. Consistent with principles of good laboratory practice, calibration is performed with at least two standard buffer solutions that span the range of pH values to be measured. For general purposes, buffers at pH 4.00 and pH 10.00 are suitable. The pH meter has one calibration control to set the meter reading equal to the value of the first standard buffer and a second control to adjust the meter reading to the value of the second buffer. A third control allows the temperature

title: PH 16

text: PH-16 are redeveloped 13 buildings and 10 have been demolished. The other two buildings are not renovated and are currently empty. 1 of which is to be redeveloped in 2012. (As at 4 February 2012) PH 16 The PH 16 (German: "Punkthochhaus mit 16 Geschossen" (a skyscraper with 16 floors)) is a type of industrial housing in East Germany. The PH 16 has 132 apartments, one or two small commercial units on the ground floor, as well as parking and trash rooms within the building. The development was primarily via two internal lifts and an H-shaped canal system on each

title: PH meter

text: instructions for cleaning and maintaining their probe designs. For illustration, one maker of laboratory-grade pH gives cleaning instructions for specific contaminants: general cleaning (15-minute soak in a solution of bleach and detergent), salt (hydrochloric acid solution followed by sodium hydroxide and water), grease (detergent or methanol), clogged reference junction (KCl solution), protein deposits (pepsin and HCl, 1% solution), and air bubbles. The German Institute for Standardization publishes a standard for pH measurement using pH meters, DIN 19263. Very precise measurements necessitate that the pH meter is calibrated before each measurement. More typically calibration is performed once per day of operation.

title: .ph

text: of the .ph domain registry. On October 1, 1999, the PH Domain Foundation launched a fully automated online system for domain registration. It also launched a flat .ph domain space, enabling people to register domains like "domainname.ph". Lifetime domain registration was halted, and all domains registered after October 1 subsequently carried expiration dates. These domain owners had to pay a fee to renew their domains. At around this period, the "for-profit" business and technical side of the PH Domain Foundation became identified as dotPH. Activities related to domains and the business were now attributed to dotPH, such as the resolution

title: Impedance–pH monitoring

text: symptoms in a statistically meaningful manner. Patients with a positive impedance–pH monitoring test may benefit from acid-reduction therapy such as fundoplication surgery or endoscopic fundoplication techniques. Impedance–pH monitoring Impedance–pH monitoring is a technique used in the diagnosis of gastroesophageal reflux disease (GERD), by monitoring both impedance and pH. Patients with ongoing symptoms while on proton-pump inhibitor (PPI) therapy are commonly diagnosed with impedance–pH monitoring while continuing their medications. The impedance–pH monitoring diagnostic test determines the frequency of reflux episodes and the time relationship of reflux episodes and symptoms. The impedance–pH monitoring test determines if the patient's symptoms are related to

title: Impedance–pH monitoring

text: Impedance–pH monitoring Impedance–pH monitoring is a technique used in the diagnosis of gastroesophageal reflux disease (GERD), by monitoring both impedance and pH. Patients with ongoing symptoms while on proton-pump inhibitor (PPI) therapy are commonly diagnosed with impedance–pH monitoring while continuing their medications. The impedance–pH monitoring diagnostic test determines the frequency of reflux episodes and the time relationship of reflux episodes and symptoms. The impedance–pH monitoring test determines if the patient's symptoms are related to acid reflux, related to nonacid reflux, or not related to reflux of any type. A positive GERD diagnosis is made if acid or nonacid reflux precedes

title: Oilfield scale inhibition

text: initially dispersed in production systems until accumulation of stable crystals of insoluble sulfates and scale growth occur at nucleation centers. Uneven pipeline surfaces and production equipment such as pumps and valves cause rapid scale growth to levels that can block pipelines. The scaling-tendency of an oil-well can be predicted based on the prevailing conditions such as pH, temperature, pressure, ionic strength and the mole fraction of CO in the vapor and aqueous phases. For instance the saturation index for CaCO scale is calculated using the formula; F= {[Ca][CO]}/K Where F is the scale saturation ratio, defined as the ratio of

title: Concret PH

text: Concret PH Concret PH (1958) is a musique concrète piece by Iannis Xenakis, originally created for the Philips Pavilion (designed by Xenakis as Le Corbusier's assistant) and heard as audiences entered and exited the building (PH = "paraboloïdes hyperboliques", "concret" = reinforced concrete/musique concrète). Edgard Varèse's "Poème électronique" was played once they were inside the building. At 2 1/2 minutes long and focused primarily on density, "Concret PH" was created in the Philips office in Paris (Varèse having exclusive access to the studio with spatialization capabilities established in Eindhoven) or at the Groupe de Recherches Musicales. The only sound source

title: Soil pH

text: growth shuts down. In soils with a high content of manganese-containing minerals, Mn toxicity can become a problem at pH 5.6 and lower. Manganese, like aluminium, becomes increasingly soluble as pH drops, and Mn toxicity symptoms can be seen at pH levels below 5.6. Manganese is an essential plant nutrient, so plants transport Mn into leaves. Classic symptoms of Mn toxicity are crinkling or cupping of leaves. Soil pH affects the availability of some plant nutrients: As discussed above, aluminium toxicity has direct effects on plant growth; however, by limiting root growth, it also reduces the availability of plant nutrients.

title: Hall PH

text: PH-1, which were fitted with more powerful engines and a partly enclosed cockpit for the pilots. The Coast Guard later ordered seven PH-2 aircraft, similar to the PH-1 but with armament removed, and seven PH-3 units with armament reinstated and a fully enclosed cockpit for the pilots. Delivery of the PH-1 commenced in October 1931, equipping VP-8 from 1932, operating from the seaplane tender and from bases at Pearl Harbor, Midway Atoll, and the Panama Canal Zone. It was replaced by the Consolidated PBY-1 Catalina in 1937. Production of the PH recommenced in June 1936 to meet an order for

title: Esophageal pH monitoring

text: pH sensors has been used to measure the degree of esophageal acid exposure in both distal and proximal esophagus. The ideal location for pH measurement to confirm the diagnosis of the laryngopharyngeal reflux is the pharynx and new studies have focused on the development of a new pH sensor which can function in the challenging environment of the oropharynx. Esophageal pH monitoring Esophageal pH monitoring is the current gold standard for diagnosis of gastroesophageal reflux disease (GERD). It provides direct physiologic measurement of acid in the esophagus and is the most objective method to document reflux disease, assess the severity

title: PH-sensitive polymers

text: include carboxylic acids (-COOH), sulfonic acids (-SOH), phosphonic acids, and boronic acids. Polyacids accept protons at low pH values. At higher pH values, they deprotonate and become negatively charged. The negative charges create a repulsion that causes the polymer to swell. This swelling behavior is observed when the pH is greater than the pKa of the polymer. Polybases are the basic equivalent of polyacids and are also known as cationic polymers. They accept protons at low pH like polyacids do, but they then become positively charged. In contrast, at higher pH values they are neutral. Swelling behavior is seen when

title: PH meter

text: sold millions of the units. In 2004 the Beckman pH meter was designated an ACS National Historic Chemical Landmark in recognition of its significance as the first commercially successful electronic pH meter. The Radiometer Corporation of Denmark was founded in 1935, and began marketing a pH meter for medical use around 1936, but "the development of automatic pH-meters for industrial purposes was neglected. Instead American instrument makers successfully developed industrial pH-meters with a wide variety of applications, such as in breweries, paper works, alum works, and water treatment systems." In the 1970s Jenco Electronics of Taiwan designed and manufactured the

title: PH meter

text: potential across the bulb. The electronic amplifier detects the difference in electrical potential between the two electrodes generated in the measurement and converts the potential difference to pH units. The magnitude of the electrochemical potential across the glass bulb is linearly related to the pH according to the Nernst equation. The reference electrode is insensitive to the pH of the solution, being composed of a metallic conductor, which connects to the display. This conductor is immersed in an electrolyte solution, typically potassium chloride, which comes into contact with the test solution through a porous ceramic membrane. The display consists of

title: PH-sensitive polymers

text: (swollen weight-deswelled weight)/deswelled weight *100% and determined by massing polymers before and after swelling. This indicates how much the polymer swelled upon a change in pH. The pH at which a significant structural change in how the molecules are arranged is observed. This structural change does not involve breaking bonds, but rather a change in conformation. For example, a swelling/deswelling transition would constitute a reversible conformational change. The value of the pH critical point can be determined by examining swelling percentage as a function of pH. Researchers aim to design molecules that transition at a pH that matters for the

title: Esophageal pH monitoring

text: A reflux episode is defined as esophageal pH drop below four. Esophageal pH monitoring is performed for 24 or 48 hours and at the end of recording, a patient's tracing is analyzed and the results are expressed using six standard components. Of these 6 parameters a pH score called Composite pH Score or DeMeester Score has been calculated, which is a global measure of esophageal acid exposure. A Demeester score > 14.72 indicates reflux. The widespread prescription of proton pump inhibitors (PPI) by primary care physicians has resulted in a change in pattern of GERD in patients who use these

title: What Is the What

text: writes: "Over the course of many years, Dave and I have collaborated to tell my story... I told [him] what I knew and what I could remember, and from that material he created this work of art." The book is typical of Eggers' style: blending non-fictional and fictional elements into a non-fiction novel or memoir. By classifying the book a novel, Eggers says, he freed himself to re-create conversations, streamline complex relationships, add relevant detail and manipulate time and space in helpful ways—all while maintaining the essential truthfulness of the storytelling. However, not all critics were impressed. Lee Siegel sees

title: PH

text: cell containing the solution of unknown pH is measured. The difference between the two measured emf values is proportional to pH. This method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/"z" is ideally equal to formula_4 the "Nernstian slope". To apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has an in-built reference electrode. It is calibrated against buffer solutions of known hydrogen ion activity. IUPAC has proposed the use of a set of buffer solutions of known H activity. Two or

title: PH

text: exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation, pH stands for "power of hydrogen". It has also been suggested that the "p" stands for the German "Potenz" (meaning "power"), others refer to French "puissance" (also meaning "power", based on the fact that the Carlsberg Laboratory was French-speaking). Another suggestion is that the "p" stands for the Latin terms "pondus hydrogenii" (quantity of hydrogen), "potentia hydrogenii" (capacity of hydrogen), or potential hydrogen. It is also suggested that Sørensen used the letters "p" and "q" (commonly paired letters in mathematics) simply to label the test

title: PH Grand Piano

text: PH Grand Piano The PH Grand Piano, or simply the PH Piano, is a piano model designed by Danish architect and writer Poul Henningsen. The design was the result of a commission from the Andreas Christensen manufacturing company who wanted a piano which was both functional and modern. In 1935 Henningsen designed the PH Pianette for the same manufacturer. The piano is on display in several museums of art and design, including the Metropolitan Museum in New York and the Danish Design Museum in Copenhagen. It was also used by Alvar Aalto for the music room in his Villa Mairea.

title: PH Grand Piano

title: Soil pH

text: of the expansion of the cells of the rhizodermis, leading to their rupture; thereafter it is known to interfere with many physiological processes including the uptake and transport of calcium and other essential nutrients, cell division, cell wall formation, and enzyme activity. Proton (H ion) stress can also limit plant growth. The proton pump, H-ATPase, of the plasmalemma of root cells works to maintain the near-neutral pH of their cytoplasm. A high proton activity (pH within the range 3.0–4.0 for most plant species) in the external growth medium overcomes the capacity of the cell to maintain the cytoplasmic pH and

title: PH 16

text: PH 16 The PH 16 (German: "Punkthochhaus mit 16 Geschossen" (a skyscraper with 16 floors)) is a type of industrial housing in East Germany. The PH 16 has 132 apartments, one or two small commercial units on the ground floor, as well as parking and trash rooms within the building. The development was primarily via two internal lifts and an H-shaped canal system on each floor, which served both 9 apartments. An achievable via a staircase Notbalkon served primarily as an escape route. Originally created next to the stairwell garbage disposals were operated infrequently. About 400 people lived in a

title: Hall PH

text: for anti-submarine patrols (particularly during the Operation Drumbeat U-boat attacks off the East coast of the United States in 1942) as well as continuing search and rescue operations. The Coast Guard continued operating the PH-2 and -3 until 1944. Hall PH The Hall PH was an American flying boat of the 1930s. It was a twin-engined biplane, developed from the Naval Aircraft Factory PN and could hence trace its lineage back to the Felixstowe flying boats of World War I. The PH was purchased in small numbers by the United States Navy and the United States Coast Guard. It remained