What is litmus? | eNotes What is litmus? william1941 | College Teacher | (Level 3) Valedictorian Posted on October 20, 2010 at 5:03 PM I think you are referring to litmus in the context of the litmus test which is performed to identify whether a substance is acidic or alkaline. Litmus is a mixture of different dyes. These are extracted from different types of lichen. The dye is usually used after it has been applied on paper and can then be used to measure pH in the range 4.5- 8.3. Litmus paper turns red when it is exposed to acidic substances and blue when it is exposed to alkaline substances. The use of litmus in the study of chemicals is quite old with the first use dating back to 1300 AD. like 1 dislike 0 October 21, 2010 at 11:58 AM Litmus is a mixture of dyes obtained from litchens. It is mainly used to test the acidity or alkalinity of a solution. There are red and blue litmus papers.

If a red litmus paper is put into an alkaline solution, it will turn blue and if a blue litmus paper is put into an alkaline solution, it will remain blue (no change). If a blue litmus paper is put into an acidic solution, it will turn red and If a red litmus paper is put into an acidic solution, there will be no change. like 0 dislike 0 October 20, 2010 at 6:41 PM Litmus is a water-soluble mixture of different dyes extracted from lichens, specially Roccella tinctoriaThe mixture has CAS number 1393-92-6. It is often absorbed on to filter paper. The resulting piece of paper or solution with water becomes a pH indicator (one of the oldest), used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions, the color change occurring over the pH range 4.5-8.3 (at 25°C).

The color changes occur at about 8.3 and 4.5 pH units respectively.Neutral litmus paper is purple in color.[ like 0 dislike 0 General Chemistry Online: FAQ: Acids and bases: What are some natural acid/base indicators? Next Question What are some natural acid/base indicators? A visual acid-base indicator is just a weak acid with differently colored acid and conjugate base forms. Flower and leaf pigments often fit this description. For example, take rose petals and crush them with alcohol; you have an acid/base indicator solution. Stew some red cabbage and pour off the juice; you have an acid/base indicator solution. Many indicators can be extracted from plants; others (like phenolphthalein *) and methyl orange are synthetic. Here are a few 'natural' acid/base indicators. For a longer list of house and garden materials that can be used to make acid-base indicators, see a related question . Alizarin is an orange dye present in the root of the madder plant; it was used to dye wool in ancient Egypt, Persia, and India. In an 0.5% alcohol solution, alizarin is yellow at pH 5.5 and red at pH 6.8.

Several synthetic modifications of alizarin are also used as acid/base indicators. Cochineal is an acid-base indicator made from the bodies of dried female cochineal insects, found in Mexico and Central America. You'll have to grind about 70,000 insects to make one pound of dry indicator. The powder is about 10% carminic acid, which is yellow in acidic solution, and deep violet in alkaline solution. Cochineal solutions are not used much as acid/base indicators these days. Curcumin, or tumeric yellow, is a natural dye found in curry powder. It turns from yellow at pH 7.4 to red at pH 8.6. Esculin is a fluorescent dye that can be extracted from the leaves and bark of the horse chestnut tree. You'll need to shine a black (ultraviolet) light on the indicator to get the full effect. Esculin changes from colorless at pH 1.5 to fluorescent blue at pH 2. Anthocyanin is probably the most readily available acid/base indicator; it is the plant pigment that makes red cabbage purple, cornflowers blue, and poppies red.

It changes color from red in acid solution to purplish to green in mildly alkaline solution to yellow in very alkaline solution. The color changes for red cabbage juice are shown to the right. Litmus is a blue dye extracted from various species of lichens. Although these lichens grow in many parts of the world, almost all litmus is extracted and packaged in Holland. Litmus is red at pH 4.5 and blue around pH 8.3. While most litmus is used to make litmus papers, some is used as a coloring for beverages. Logwood is a dye obtained from the heartwood of a tree that grows in Central America and the West Indies. The extract contains hematoxylin and hematein, which turn bright red in alkaline solution.

Ph Indicators Ph Indicators Basic Fuchsine Dye/Stain (Solid/Powder) 50g 1% Aqueous Solution LDPE Dropper Bottle RED → COLORLESS For pH 12.0 to 14.0 C 20 H 20 ClN 3 CAS No: 632-99-5 337.86 g/mol 10g (0.35 oz.) They are soft, with a hardness of less than 1, about the same as or less than talc. They possess a strong metallic lustre and a green yellow color. They leave dark greenish streaks on...

C 20 H 20 ClN 3 CAS No: 632-99-5 337.86 g/mol 50g (1.8 oz.) $16.00 Aniline Blue Alcoholic Stain 30ml C 27 H 28 Br 2 O 5 S CAS No: 76-59-5 624.38 g/mol 10g (0.35 oz.) Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a... C 27 H 28 Br 2 O 5 S CAS No: 76-59-5 624.38 g/mol 50g (1.8 oz.) Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a...

1% Solution in Ethyl Alcohol Stain for cellulose Water Based Aqueous Solution 0.1% Solution Molecular formula C20H20N3·HCl Molar mass 337.86 g/mol Melting point 200°C Solubility in water 2650 mg/L (25°C) Basic fuchsine, also known as basic violet 14, basic red 9, pararosanaline or CI 42500 Fuchsine is a component in the... Other names: Malachite green G, Emerald green, Solid green JJO, Diamond green G, Aniline green, Benzaldehyde green, Fast green J CAS number 633-03-4 Packaged in a LDPE Dropper Bottle Brilliant Green is one of the triarylmethane dyes. It is...

$13.00 Brilliant Yellow Aqueous Solution CAS:3051-11-4 Molecular Formula: C26H18N4Na2O8S Bromocresol Green Aqueous solution CAS:76-60-8 Packaged in 60ml dropper bottle Bromocresol Green (BCG) is a dye of the triphenylmethane family (triarylmethane dyes), which is used as a pH indicator and as a tracking dye for DNA agarose gel electrophoresis 0.1% Solution In Ethyl Alcohol Ph 3.8 to 5.4 Indicator Turns YELLOW → BLUE CAS 76-60-8 2oz, 60Ml LDPE Dropper Bottle $15.00 Besides its primary function as an indicator, Bromocresol Purple is used in medical laboratories to measure albumin, and as an addition to acid stop baths used in photographic processing as an indicator that the bath has reached neutral pH and... Yellow at pH 3.0 Purple at pH 4.6 Extensively Used in Biodiesel Bromothymol blue is a pH indicator for weak acids and bases.

It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7), such as managing the pH of pools and fish tanks.

$15.00 Bromothymol Blue, 0.04% Aqueous Solution In Ultra Pure Water 30ml -60ml Packaged in Dropper Bottles Larger Sizes are in standard Cylinder Bottles Bromothymol Blue, 0.1% Aqueous Solution In Ultra Pure Water 30ml -60ml Packaged in Dropper Bottles Larger Sizes are in standard Cylinder Bottles 0.04% Aqueous Solution Packaged in a LDPE Dropper Bottle $8.00 CAS number 548-62-9 PubChem 11057 ChemSpider 10588 UNII J4Z741D6O5 EC number 208-953-6 UN number 3077 Packaged in a LDPE Dropper Bottle 0.0 - 1.8 Yellow To Blue 0.02% in water Crystal Violet Stain CAS:548-62-9 Packaged in a 60ml dropper bottle Amber Glass Tamper Sealed Bottle 1fl oz, 30ml Used as a kit component in Gram Stain Procedure $16

.00 Litmus 0.5% Aqueous Solution Indigo carmine, or 5,5'-indigodisulfonic acid sodium salt, also known as indigotine or FD&C Blue #2 is a pH indicator with the chemical formula C16H8N2Na2O8S2.

It is approved for use as a food colorant in the United States and the EU and has... Classic test for the presence of blood at a crime scene! Kastle-Meyer reagent contains reduced phenolphthalein indicator in a basic solution. Simply wipe a presumptive bloodstain with a cotton swab, add a drop of the reagent, and then apply a... One of the oldest forms of pH indicator, used to test materials for acidity Blue litmus turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions pH range 4.5-8.3 at 25 °C Litmus is a water-soluble mixture of different dyes extracted from lichens $15.00 Self made acid/base indicators, PH indicators, homemade litmus paper A lot of plants with colors other than green are usable as a PH indicators. Some of the most commonly known ones are: Litmus, a dye extracted from lichens. Red cabbage extract The litmus paper is used in labs around the world to test whether a solution is acidic or basic. The advantage of litmus is that it can be stored over many years and remains usable.

Litmus PH indicator above ph 8.5 Red cabbage Red cabbage is cheap, very color intensive and can actually indicate the PH of a solution in more find grained steps. The problem is it works best with fresh cabbage and the extract is only usable for a couple of weeks. It is however still a very useful "home made" PH indicator and it's a nice experiment for a science class in school. To make red cabbage extract you cut a few leaves of red cabbage into small slices or you can put them into a mixer. red cabbage leaves Add a 50-70% alcohol water solution and let it sit for about 15 minutes. I recommend to use real ethanol and not isopropyl alcohol if you do this experiment with children where it is difficult to avoid that some get in contact with the alcohol. Both ethanol and isopropyl-alcohol are toxic but ethanol is less toxic to humans. Isopropyl causes kidney damages even if it is just used externally over a longer period of time. Short exposure of a hand or the inhalation of the vapor for a few minutes is supposedly not dangerous but ethanol is for sure less dangerous.

red cabbage extraction process Separate the cabbage from the now dark colored alcohol solution by pressing it through a cheese cloth and fill the red cabbage indicator solution into a small bottle for storage. red cabbage extract PH indicator To test the PH of any liquid just add a few drops of the red cabbage extract and then compare the color with the following table. Red cabbage extract PH indicator ph 0-1 ph 11-14 More stable PH indicators Red cabbage is a very good PH indicator but is looses its ability to indicated the PH over a couple of weeks or month depending on how you store the solution. More stable PH indicators that can easily made at home are: Turmeric (the yellow part of Curry Powder) => very stable, usable for many years Radish peels => somewhat stable, usable for a few month Elderberry => stable, usable for a year or two Radish is similar to red cabbage in the sense that it can indicate the PH in many fine grained steps where as Turmeric and Elderberry have just two colors. Turmeric as PH indicators Turmeric powder can be found in the spices section of you supermarket. It is as well the yellow part of Curry Powder. The best way to store turmeric over longer periods is to store it as powder.

To use it just mix a bit of powder with water. Turmeric PH indicator above ph 8.6 Radish peels as PH indicator Radish extract is produced in the same way as red cabbage extract. Just peel the red skin off several radishes and then extract the dye using an alcohol water solution. radish ph 11-14 European Elder (sambucus nigra) The European Eldertree is a shrub that grows best in humid soil and it can get up to 15 feet (5m) high. You can find this bush also in the colder parts of north America (Canada and northern states of the USA). It has white flowers in June and around August time small black looking berries. sambucus nigra in June/July sambucus nigra, berries (in August) The juice from the berries makes an indicator that works exactly like litmus. Use a hand full of dark ripe elder-berries and add about the same volume of water. Cook the berries in the water for about 2 minutes. Filter through a cheese cloth and squeeze it to get as much juice as possible. Add a bit of pure alcohol (ethanol or propanol) to the liquid as a preservative.

You can as well soak acid free art paper or a kitchen sponge towel (kitchen paper towel) with the juice and let it dry to make "litmus paper". Note that the elder berries are already slightly acidic (mostly ascorbic acid). You have to add a few drops of a soda and water solution to get it into the neutral range or you could leave it as it is and use it as an indicator for the higher ph ranges. Elder berry PH indicator (similar to litmus) below ph 4 above ph 8 Both the paper and the liquid are very stable and function for a few years. Home-made "litmus paper" made from elderberry juice. It's stable and almost as good as real litmus paper.

Lichens and People: Uses, Benefits, and Potential Dangers | Owlcation Lichens and People: Uses, Benefits, and Potential Dangers Lichens and People: Uses, Benefits, and Potential Dangers Updated on January 17, 2017 Joined: 6 years agoFollowers: 1,256Articles: 431 28 Several types of lichens growing on a tree branch | Source Advertisement Interesting and Useful Organisms Lichens are interesting organisms. They are an important part of nature and are often useful for humans. They provide us with dyes, scents for perfumes, and sometimes food. In the future, they may also provide us with antibiotics and sunscreen chemicals. Some species can withstand high levels of radiation. Others can be used as biological sensors that give us information about the environment. Lichens have a wide variety of shapes and body forms. They also have many possible colours, including black, grey, white, green, blue-grey, yellow, orange, red, or brown. Despite their appearance, they aren't plants. Their body contains both a fungus and an alga. Each organism helps the other in some way, creating a beneficial partnership.

The word "lichens" is generally pronounced "likens". In some places it's pronounced as it's spelled, however, and rhymes with kitchens. An orange crustose lichen growing on a rock on a beach | Source Advertisement What Are Lichens? Lichens are beautiful and somewhat mysterious organisms that are classified into three main types, based on the form of their body, or thallus. Foliose types have a leaf-like appearance. Fruticose types have a highly branched form. They may be erect or hanging. Crustose types look like a crust that has formed on a surface. Intermediate and unusual forms of lichens exist. For example, scaly types look like a cross between a crustose form and a foliose form. Jelly lichens live in moist areas and have a gelatinous appearance when wet. Unlike a plant, a lichen doesn't have roots, stems or leaves. It's attached to its substrate by filaments called rhizines or by a single, central extension of the thallus called a holdfast.

Most of the water and nutrients that the thallus needs are absorbed from the surrounding air and raindrops instead of through the rhizines or holdfast. Lichens are scientifically classified according to the fungus that they contain and are placed in the Fungi kingdom. The fungus is often said to be "lichenized" when it's combined with an alga. Advertisement Exploring Lichens in a Seattle Cemetery Habitats, Substrates, and Ecology Lichens are found in many different habitats, including temperate and tropical rainforests, deserts, mountains, the tundra, snowy and icy areas, and seashores. In addition, they grow on many different substrates, including apparently smooth ones. Possible substrates include: wood and bark A foliose lichen growing in a cemetery | Source Symbiosis A lichen is an example of symbiosis—a relationship in which two organisms live in a close association. The alga in the partnership may be a green alga or an organism that used to be called a blue-green alga but is now known as a cyanobacterium. Occasionally both an alga and a cyanobacterium are present.

The fungus nearly always belongs to a group known as the ascomycetes. Like most other fungi, the fungal component of a lichen consists of branching, thread-like structures called hyphae. The algal cells are generally located in the middle of the lichen and are surrounded by hyphae. In jelly lichens the fungal hyphae and algal cells are mixed uniformly. The algal cells make food for both themselves and the fungus. They contain chlorophyll, which absorbs sunlight. The alga uses the light energy to make carbohydrate from carbon dioxide and water. Fungi don't contain chlorophyll and can't produce their own food. The fungus in a lichen helps the alga by protecting it. Advertisement In 2016, scientists made a surprising discovery. They found that many lichens consist of a fungus, an alga or a cyanobacterium, and a yeast belonging to a group known as the basiodiomycetes. The presence of the yeast was unexpected. The researchers think that this organism makes chemicals that protect the lichen from microbes and predators. Xanthoria elegans is also known as the elegant sunburst lichen.

It's classified as a foliose type, although its centre often appears to be crustose. | Source Dyes for Wool and Fabric Many lichens are a grey colour when they're dry. When a lichen is moistened and absorbs water, however, the algal cells give it a deeper hue. The fungus component is often colourless, but in some cases it contains a pigment that gives the lichen a vivid color. Making wool and fabric dyes from lichens is an ancient process that is still performed today. Suitable specimens are collected, cut into pieces and added to water. Ammonia is often added to the water. At one time urine was commonly used as the water-ammonia solution. The mixture is left for several weeks in order for the dye to appear. The dye made from a lichen often has a different colour from the intact organism. Brown, gold, orange, green, purple, blue and red colours are all possible, depending on the species of lichen used and the type of extraction process. Modern wool and fabric dyers often emphasize conservation as they collect lichens.

They tend to gather specimens that have already become detached from their substrate or that are growing in a place from which they are likely to be removed, such as trees that have died. (Lichens don't harm trees.) The red reproductive structures of the British soldiers lichen, or Cladonia cristatella; the lichen is growing in the company of mosses | Source British soldiers is a fruticose lichen found in Ontario and the northeastern part of the United States. The name is said to be derived from the red uniforms worn by British troops during the American revolution. A Useful Dye and an Interesting Pigment Litmus Paper Litmus paper is very commonly used as an acid-base indicator, especially by students who need to know only the approximate pH of a substance. Litmus is a mixture of dyes extracted from specific lichens, especially Rosella tinctoria. Litmus paper is made from filter paper that has been treated with the dye. Neutral litmus paper is purple in color. It turns red when exposed to an acid and blue when exposed to a base (alkali). Natural Sunscreens Xanthoria parietina is a foliose lichen which contains a yellow pigment called parietin.

This pigment absorbs ultraviolet radiation, acting as a sunscreen to protect the algal cells inside the lichen. Some other lichens contain sunscreens, too. It's been suggested that the protective chemicals could be useful in human sunscreens. Xanthoria parietina is a foliose lichen that has a high resistance to pollution, especially in the form of nitrogen; the orange cup-like structures are apothecia and produce reproductive spores | Source Usnea often hangs from branches and is sometimes known as old man's beard. This is Usnea filipendula. | Source Antibiotics, Preservatives, and Toxins Usnea Usnic acid has been found in several lichen species, including members of the Usnea genus. In natural medicine Usnea is used as an antibiotic and an anti-inflammatory substance. It's also used in some products as a preservative. Tests in laboratory equipment and lab animals show that usnic acid has antimicrobial properties and kills bacteria, fungi and viruses. It also decreases inflammation and prevents some types of cancer cells from reproducing. Unfortunately, it may cause serious liver damage in humans. Clinical tests of the effectiveness of usnic acid in the human body are lacking.

Wolf Lichen The wolf lichen (Letharia vulpina) has a bright yellow-green colour and grows in Europe and western North America. It contains a yellow chemical called vulpinic acid, which is poisonous to mammals. In the past, wolf lichen mixed with ground glass and meat was used as a poison for wolves. It's unknown if the lichen or the glass was most responsible for the death of the animals. Wolf lichen has also been used for dye extraction and was once used medicinally by native peoples. Lab research shows that vulpinic acid can kill certain kinds of bacteria. As in the case of usnic acid, if vulpinic acid is proven to be helpful for humans, we need to find a way to prevent the chemical from hurting us before we can use it as an antibiotic. It's important to note that even though a chemical is antibacterial in isolated cells and in lab animals it may not have the same effect inside our body. Letharia vulpina or wolf lichen | Source Ingredients in Perfumes and Deodorants Oakmoss Oakmoss (Evernia prunastri) is used to provide scents and fixatives for perfumes.

It grows in Europe and North America but is especially valued in France. It lives on oak trees as well as other trees and is a fruticose lichen, not a moss. Both essential oils and absolutes are extracted from the oakmoss. Essential oils are usually obtained by steam distillation. Absolutes are obtained by solvent extraction and are generally more concentrated than essential oils. The extracts of oakmoss are said to have a lovely earthy scent that resembles the aroma of moss and has an undertone of pine. Some oakmoss extracts advertise the fact that they are low in atranol. This chemical is allergenic for some people, so it's worth seeking products that have little or no atranol. Pseudevernia furfuracea Pseudevernia furfuracea is another fruticose lichen used in the perfume industry. The lichen was used to fill the body cavity of Ancient Egyptian mummies. It's not known if the lichen was used as a preservative or to provide a pleasant scent. Today lichen components are used in deodorants as well as perfumes because of their pleasing aroma. Oakmoss is a lichen, despite its name.

| Source Lichens as Food for People While we shouldn't pick up a lichen from a neighbourhood rock or tree and eat it, some species are eaten by humans. Many species are mildly toxic, a few are poisonous and most are indigestible in their raw form. Some cultures have learned to prepare lichens in a way that improves their digestibility, however, and even makes them a delicacy. Reindeer moss, or Cladonia rangiferina, is a fruticose lichen that is a staple food of reindeer and caribou. (This is yet another "moss" that is really a lichen.) Some Arctic inhabitants mix the partly digested lichen from caribou stomachs with raw fish eggs. The result is a concoction known as "stomach ice cream". Umbilicaria esculenta is a black foliose lichen that grows on rocks. It's used in Asian cuisine after being fried. Umbilicaria lichens are often knows as rock tripe. The North American version was used as an emergency food by early explorers. Some lichens are boiled and mixed with fruit and flavouring agents such as onions before being eaten.

With a few exceptions, however, lichens are generally used as food in famine situations instead of by choice. Reindeer moss grows on the ground. It forms patches that often resemble foam or a sponge when viewed from a distance. | Source A bioindicator is a species that indicates the health of the environment via its presence, function or behaviour. Lichens can act as bioindicators. Pollution and Dehydration Some lichens are very tolerant to pollutants such as nitrogen and sulphur compounds, while others are very sensitive to the presence of one or both of these chemicals. People who can identify lichens can learn about local environmental conditions by observing which species are present. The species act as bioindicators. Lichens have a high resistance to damage by dehydration and the ability to quickly absorb a large quantity of water after dehydration ends. This property has enabled them to be used as wound dressings and diapers by people in the past. The organisms stop photosynthesizing when they dry out and start producing food again as they absorb water. A Lichen Survey in London, England Radiation Exposure Lichens absorb and store radioactive substances, such as cesium and strontium compounds, without apparent harm.

Their thalli can be tested for the presence of radioactive compounds in order to learn about their environment. At least some species of lichen are very resistant to dangerous radiation. In a 2005 experiment, two species spent sixteen days in space inside an orbiting satellite. Here they were exposed to "massive" doses of ultraviolet and cosmic radiation. When they returned to Earth they had nearly the same photosynthetic ability as before the flight. In addition, most of the lichens' cells had no observable damage when examined under high magnification. An interesting tree trunk covered with fruticose and foliose lichens as well as moss | Source Searching for Lichens Just about any walk that I take ends up as a nature walk. Looking for lichens and photographing them is an enjoyable part of my journey. They are sometimes very obvious, as in the photo above. Others may be overlooked by someone who doesn't pause to look at tree bark, twigs and rocks. The smaller parts of nature often live on these surfaces. It's fun to examine lichens and other creatures with or without a magnifying glass.

It's also interesting to think about the ways in which they are used by humans and the possible ways in which they may help us in the future. References Indicators - GiantScience GiantScience Indicators Investigation at bottom of page An Indicator is a substance that can tell us if another substance that it is in contact with is acidic or alkaline. Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccella tinctoria. The mixture has CAS number 1393-92-6. It is often absorbed onto filter paper. The resulting piece of paper or solution with water becomes a pH indicator (one of the oldest), used to test materials for acidity. Litmus Ranges ACID pH < 4.3 NEUTRAL pH > 8.3 BASE pH is a complicated measure of the amount of H+ ions that are in the mix, A low pH means a lot of H+ ions, a high value indicates that there is a desire for more H+ ions in the solution. Naturally occurring pH indicators 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.

Extracting anthocyanins from red cabbage leaves or the skin of a lemon to form a crude acid-base indicator is a popular introductory chemistry demonstration. Anthocyanins can be extracted 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). An exhaustive list would be beyond the scope of this article - WIKIPEDIA Why not test some plants to see if they could be used as acid/base indicators TO MAKE RED CABBAGE INDICATOR Materials: We could now find the range of turning pH for the red cabbage indicator and also to view the different colours of Universal Indicator 1) Arrange 7 test tubes in a rack 2) Pour 10ml of hydrochloric acid into the first test tube (pH 1). 3) Pour 1ml from the first test tube into the next test tube and add 9ml of water (pH 2). 4) Pour 1ml from the second test tube into the third test tube and add 9ml of water (pH 3).

5) Continue this procedure until all test tubes have 10ml of solution (pH 4  7). 6) Add 2-3 drops of universal indicator to each test tube. 7) Record observations by colouring the appropriate box in the result table. 8) Clean test tubes and repeat steps 1)-7) using the red cabbage indicator. 9) Clean test tubes and repeat steps 1)-7) starting with sodium hydroxide and using universal indicator (pH 14  8). 10) Clean test tubes and repeat steps 1)-7) starting with sodium hydroxide and using red cabbage indicator. 11) Record observations by colouring the appropriate box in the result table. So Indicators and their colours, we see that they change different colours in different solutions but what makes one change might not effect another indicator. So do we need to learn them all ? NO!

well except to know that Methyl Orange turns Pink at pH 7 A full list of Indicators is here A Listing of most of the commercially available indicators Indicator pH Range Quantity per 10 ml Acid Base Thymol Blue 1.2-2.8 1-2 drops 0.1% soln. in aq. red yellow Pentamethoxy red 1.2-2.3 1 drop 0.1% soln. in 70% alc. red-violet colorless Tropeolin OO 1.3-3.2 1 drop 1% aq. soln. red yellow 2,4-Dinitrophenol 2.4-4.0 1-2 drops 0.1% soln. in 50% alc. colorless yellow Methyl yellow 2.9-4.0 1 drop 0.1% soln. in 90% alc. red yellow Methyl orange 3.1-4.4 1 drop 0.1% aq. soln. red orange Bromphenol blue 3.0-4.6 1 drop 0.1% aq.

soln. yellow blue-violet Tetrabromphenol blue 3.0-4.6 1 drop 0.1% aq. soln. yellow blue Alizarin sodium sulfonate 3.7-5.2 1 drop 0.1% aq. soln. yellow violet a-Naphthyl red 3.7-5.0 1 drop 0.1% soln. in 70% alc. red yellow p-Ethoxychrysoidine 3.5-5.5 1 drop 0.1% aq. soln. red yellow Bromcresol green 4.0-5.6 1 drop 0.1% aq. soln. yellow blue Methyl red 4.4-6.2 1 drop 0.1% aq. soln. red yellow Bromcresol purple 5.2-6.8 1 drop 0.1% aq. soln. yellow purple Chlorphenol red 5.4-6.8 1 drop 0.1% aq. soln.

yellow red Bromphenol blue 6.2-7.6 1 drop 0.1% aq. soln. yellow blue p-Nitrophenol 5.0-7.0 1-5 drops 0.1% aq. soln. colorless yellow Azolitmin 5.0-8.0 5 drops 0.5% aq. soln. red blue Phenol red 6.4-8.0 1 drop 0.1% aq. soln. yellow red Neutral red 6.8-8.0 1 drop 0.1% soln. in 70% alc. red yellow Rosolic acid 6.8-8.0 1 drop 0.1% soln. in 90% alc. yellow red Cresol red 7.2-8.8 1 drop 0.1% aq. soln. yellow red a-Naphtholphthalein 7.3-8.7 1-5 drops 0.1% soln. in 70% alc.

rose green Tropeolin OOO 7.6-8.9 1 drop 0.1% aq. soln. yellow rose-red Thymol blue 8.0-9.6 1-5 drops 0.1% aq. soln. yellow blue Phenolphthalein 8.0-10.0 1-5 drops 0.1% soln. in 70% alc. colorless red a-Naphtholbenzein 9.0-11.0 1-5 drops 0.1% soln. in 90% alc. yellow blue Thymolphthalein 9.4-10.6 1 drop 0.1% soln. in 90% alc. colorless blue Nile blue 10.1-11.1 1 drop 0.1% aq. soln. blue red Alizarin yellow 10.0-12.0 1 drop 0.1% aq. soln.

yellow lilac Salicyl yellow 10.0-12.0 1-5 drops 0.1% soln. in 90% alc. yellow orange-brown Diazo violet 10.1-12.0 1 drop 0.1% aq. soln. yellow violet Tropeolin O 11.0-13.0 1 drop 0.1% aq. soln. yellow orange-brown Nitramine 11.0-13.0 1-2 drops 0.1% soln in 70% alc. colorless orange-brown Poirrier's blue 11.0-13.0 1 drop 0.1% aq. soln. blue violet-pink Trinitrobenzoic acid 12.0-13.4 1 drop 0.1% aq. soln. colorless orange-red Universal indicator is a chemical made by combining other indicators, by doing this we have a way of measuring the pH change of a substance continuously as the reaction takes place.

Using Universal Indicator, random substances can have their acidity checked quite easily because the different indicators are combined in the test papers and we do not need many chemicals in our lab or in the field. There are more exact pH papers, they are Universal papers but they improve their accuracy by having different coloured compounds at different locations along the strip. Digital pH Meters There are many type of digital pH meters that can read the pH of substances, one of the problems with these meters is that they require calibration. for the pH meters in Hartstown community school the calibration information is here Difference Between Litmus Paper and pH Paper Home / Science & Nature / Science / Chemistry / Difference Between Litmus Paper and pH Paper Difference Between Litmus Paper and pH Paper Posted on Litmus Paper vs pH Paper Litmus Paper Litmus paper is an indicator, which can be used to determine acidic and basic solutions. Normally this comes as a paper stripe. Mixture of water-soluble dyes extracted from lichens like Roccella tinctoria are absorbed into filter paper stripes to make litmus paper. In this mixture, there are about 10- 15 types of dyes. There are two types of litmus papers as blue and red.

Red litmus paper is used to test basic solutions. Red litmus papers turn blue when encountered with a basic solution. Whereas blue litmus papers turn red when encounter with an acidic solution. The neutral litmus papers are purple in color. The color change of litmus papers is taking place over pH range 4.5-8.3 at 25 °C. Therefore, one of the disadvantages of litmus papers is that they cannot be used to determine the pH value. The strength of the acidity or the basicity also cannot be determined using litmus papers, on the other hand, the readings are instantaneous, and easy to take. Litmus papers can be used by anyone without any expertise knowledge. They only have to know which color is relevant to acidic and basic pH value. pH Paper pH is a scale, which can be used to measure the acidity or basicity in a solution. The scale has numbers from 1 to 14. pH 7 is considered as a neutral value. Pure water is said to be having pH 7. In the pH scale, from 1-6 acids are represented. Acids can be categorized into two, based on their ability to dissociate and produce protons.

Strong acids like HCl, HNO3 are ionized completely in a solution, to give protons. Weak acids like CH3COOH partially dissociate and give fewer amounts of protons. An acid with pH 1 is said to be very strong, and as the pH value increases, acidity is decreased. The pH values more than 7 indicate basicity. As the basicity increases, pH value will also increase and strong bases will have pH value 14. pH papers are indicators which are easy to use. They are common in every chemical laboratory. They come in various types as rolls, stripes, etc. Though pH meter is the best equipment to measure the pH value accurately, pH papers are the best alternative when quick and approximate measurements are needed. With the pH paper, a color chart is provided. When the pH paper in the solution, where pH should be determined, the paper will show a certain color. This color change is relevant to the pH of the solution. Sometimes the colors are not so contrasting, so it is bit difficult to determine the pH range. Therefore, one disadvantage of pH papers is determining the value. Other disadvantage is that pH papers provide a pH range, so the exact pH value of the solution cannot be determined.

However, there are lots of advantageous of pH papers too. They give fast reading, easy to use (does not need expert knowledge), portable, inexpensive, and reading are accurate for the most part. What is the difference between Litmus Paper and pH Paper? • Litmus papers can only be used to determine whether the solution is acidic or basic. But from pH papers, the pH range of the solution can be determined. • So pH papers give more precise readings than litmus papers. • Litmus papers give only two colors, either red or blue based on the pH of the solution. But pH papers give a range of different colors.

Question: Litmus is a mixture of dyes used as an indicator. It is extracted from which types of plant?
Answer: LICHENS