Answer the following question given this paragraph: As indicated in http://catalog. flatworldknowledge. com/bookhub/reader/2547 - gob-ch10_s04, weak acids are relatively common, even in the foods we eat. But we occasionally come across a strong acid or base, such as stomach acid, that has a strongly acidic pH of 12. By definition, strong acids and bases can produce a relatively large amount of hydrogen or hydroxide ions and, as a consequence, have a marked chemical activity. In addition, very small amounts of strong acids and bases can change the pH of a solution very quickly. If 1 mL of stomach acid [which we will approximate as 0.05 M HCl(aq)] is added to the bloodstream, and if no correcting mechanism is present, the pH of the blood would go from about 7.4 to about 4.9a pH that is not conducive to continued living. Fortunately, the body has a mechanism for minimizing such dramatic pH changes. The mechanism involves a buffer, a solution that resists dramatic changes in pH. Buffers do so by being composed of certain pairs of solutes: either a weak acid plus a salt derived from that weak acid or a weak base plus a salt of that weak base. For example, a buffer can be composed of dissolved acetic acid (HC2H3O2, a weak acid) and sodium acetate (NaC2H3O2, a salt derived from that acid). Another example of a buffer is a solution containing ammonia (NH3, a weak base) and ammonium chloride (NH4Cl, a salt derived from that base). Let us use an acetic acidsodium acetate buffer to demonstrate how buffers work. If a strong basea source of OH(aq) ionsis added to the buffer solution, those hydroxide ions will react with the acetic acid in an acid-base reaction: HC2H3O2(aq) + OH(aq) H2O() + C2H3O2(aq) Rather than changing the pH dramatically by making the solution basic, the added hydroxide ions react to make water, and the pH does not change much. Q: Acids are associated with a low number on which scale? Choices: - metric - acidic - ionic - ph A:
ph
Answer the following question given this paragraph: 2.3 Chemical Reactions Chemical reactions, in which chemical bonds are broken and formed, require an initial investment of energy. Kinetic energy, the energy of matter in motion, fuels the collisions of atoms, ions, and molecules that are necessary if their old bonds are to break and new ones to form. All molecules store potential energy, which is released when their bonds are broken. Four forms of energy essential to human functioning are: chemical energy, which is stored and released as chemical bonds are formed and broken; mechanical energy, which directly powers physical activity; radiant energy, emitted as waves such as in sunlight; and electrical energy, the power of moving electrons. Chemical reactions begin with reactants and end with products. Synthesis reactions bond reactants together, a process that requires energy, whereas decomposition reactions break the bonds within a reactant and thereby release energy. In exchange reactions, bonds are both broken and formed, and energy is exchanged. The rate at which chemical reactions occur is influenced by several properties of the reactants: temperature, concentration and pressure, and the presence or absence of a catalyst. An enzyme is a catalytic protein that speeds up chemical reactions in the human body. Q: What term is used to describe the energy of matter in motion? Choices: - frictional energy - gravitational energy - emotional energy - kinetic energy A:
kinetic energy
Q: Answer the following question given this paragraph: Q: What are the three types of isomers? Choices: - structural, Polypropylene , enatiomers - structural , chromosome - trans , enatiomers - structural, cis-trans, Polystyrene - structural, cis-trans, enatiomers A:
A: structural, cis-trans, enatiomers
Question: Answer the following question given this paragraph: The mass spectrometer measures the percent abundance of different isotopes in a given sample. Q: He mass spectrometer measures the percent abundance of different what? Choices: - reactions - organisms - Proteins - isotopes A:
Answer: isotopes
*Question*
Answer the following question given this paragraph: How Light-Dependent Reactions Work The overall purpose of the light-dependent reactions is to convert light energy into chemical energy. This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. Photosystems exist in the membranes of thylakoids. A pigment molecule in the photosystem absorbs one photon, a quantity or "packet" of light energy, at a time. A photon of light energy travels until it reaches a molecule of chlorophyll. The photon causes an electron in the chlorophyll to become "excited. " The energy given to the electron allows it to break free from an atom of the chlorophyll molecule. Chlorophyll is therefore said to "donate" an electron (Figure 5.12). To replace the electron in the chlorophyll, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O2) and hydrogen ions (H+) in the thylakoid space. Technically, each breaking of a water molecule releases a pair of electrons, and therefore can replace two donated electrons. Q: The overall purpose of the light-dependent reactions is to convert light energy into this? Choices: - photosynthesis - thermal energy - calories - chemical reactions A:
**Answer**
chemical reactions
Answer the following question given this paragraph: water that flows over the land from precipitation or melting snow or ice. Q: What substance flows over the land from precipitation or melting snow or ice? Choices: - nitrogen - lava - air - water A:
water