Name:
/25 pts
Quiz 05
Biology 101, 2012, Spring 2 Session (Aird)
Multiple Choice. Identify the choice that best completes the statement or answers the question, using upper case letters.
____ 1. A solution at pH 8 has ________ hydrogen ions than a solution at pH 5.
a. 30 times more b. 1,000 times fewer c. 30 times fewer d. 1,000 times more e. 3 times fewer
____ 2. Strong acids
a. make good buffers. b. can only be neutralized by strong bases. c. have pHs above 6.0. d. are acid
solutions in which the concentration of acid is higher than 1 Molar.
e. are acids that dissociate completely into ions when dissolved in water.
____ 3. All of the following about acids and bases are true, except
a. Acids neutralize bases to forms salts and water. b. Lichens participate in soil formation by degrading
rock with carbonic acid. c. Acids are proton donors and bases are proton acceptors. d. Bases dissolve
metals and turn litmus paper blue.
e. Nonmetal oxides combine with water to create acid precipitation.
____ 4. Avogadro’s number
a. laid the foundation for later development of the Valence Shell Electron Pair Repulsion theory.
b.
varies slightly for liquids, solids, and gasses. c. equates invisible and uncountable atoms and molecules
with masses which can be determined. d. equals 6.02 x 223 e. does not apply to noble gasses because
their outer shells are full.
____ 5. When weak acids dissolve in water, they
a. release all of their hydrogen ions, which they bind only weakly. b. dissociate into protons and strong
bases.
c. donate protons which are immediately bound by water molecules to form H3O+ ions.
d.
don’t do much, which is why they are considered weak. e. release hydrogen ions which float around by
themselves in the solution.
____ 6. Although carbon dioxide contains carbon, it is not considered an "organic" compound because
a. it is not found in the earth.
b. the carbons are not in chains or rings.
c. it is too small.
d. no
hydrogen is present. e. it is not present in living cells.
____ 7. A reaction of sulfuric acid [H2SO4] and calcium hydroxide [Ca(OH)2] will produce water and which salt?
a. calcium sulfate. b. hydrogen hydroxide. c. They will not react. d. NaCl. e. sodium hydroxide.
____ 8. If the pH of a lake has changed from pH 7 to pH 4 due to acid precipitation,
a. the hydrogen ion concentration is 103 times greater. b. it is more healthy for aquatic organisms. c.
the hydrogen ion concentration has been reduced by 1,000-fold. d. it is now 30 times less basic. e. it
is more suitable for swimming, provided that you like pickles.
____ 9. Which of the following is a naked proton?
a. base b. sodium ion c. hydrogen ion d. acid e. hydroxyl ion
____ 10. The word "organic" signals the presence of
a. hydrogen. b. oxygen. c. sulfur. d. carbon. e. nitrogen.
____ 11. Which of the following is NOT true?
a. Acids release hydrogen ions.
b. Hydrogen bonding between water molecules gives water its
temperature-stabilizing and cohesive properties. c. Polar water molecules are attracted to salts. d. In
a neutral solution, the amounts of hydrogen and hydroxyl ions are almost equal.
e. Salts orient themselves in water because of the dipoles of the salt molecules.
A
Multiple Response. Identify one or more choices that best complete the statement or answer the question, using upper case
letters. Place all correct answers in the space provided in alphabetical order.
A
________ 12. Saturation of hydrocarbons
a. requires that all carbon-carbon bonds be single bonds.
b. affects the rigidity and flexibility of
the carbon chains. c. has to do with the number of hydrogen atoms bonded to the carbons. d.
is more typical of the fat of mammals than of birds, and fish. e. allows the hydrocarbons to pack
more tightly, making them stiffer at a given temperature.
________ 13. Which of the following is accurate?
a. Concentrations are reported in moles per Liter.
b. A mole of carbon has a mass of 12 grams.
c. A mole of any two substances has the same mass.
d. The formula mass of a compound is the
sum of the atomic masses of its constituent atoms.
e. A mole of a compound is one Avogadro’s
number of molecules.
________ 14. Which of the following is true in relation to buffers?
a. Acetic acid is important in regulating tissue pH.
b. Buffers allow organisms to maintain homeostasis.
c. Bicarbonate and phosphate are important buffers in mammals.
d. Buffers are
critical to living organisms because they stabilize blood pressure. e. A buffer consists of a mixture
of a weak acid and its conjugate base.
________ 15. Which of the following about the chemistry of acids and bases are correct?
a. The burning of fossil fuels contributes significantly to the acidification of streams, rivers, ponds,
and lakes. b. Lichens secrete bases that gradually dissolve rocks and contribute to soil formation.
c. Soda pop contains an unstable base that breaks down to carbon dioxide and water.
d. Acids
hydrolyze fats, oils and greases to form soap.
e. Fireplace ash contains large quantities of metal
oxides, which form bases when hydrated.
Matching. The following are chemical functional groups that may be part of a biologically active molecule. Answer by matching the items with the most appropriate group. Please use upper case letters. (0.5 pts each)
a.
____ 16. The ketone group
____ 17. The carboxyl group
b.
____ 18. Part of all organic acids, such as acetic acid.
c.
____ 19. The aldehyde group
d.
e.
____ 20. Found in fruit flavors, triglycerides, and phospholipids.
____ 21. The group, that with short carbon chains, causes parakeets
f.
to explode spontaneously.
____ 22. The group that forms covalent cross-links in proteins.
g.
____ 23. A weakly hydrophobic group related to methane.
h.
____ 24. The compound that plays a major role in regulation of
blood pH.
____ 25. The group on the amino-terminal end of proteins.
2
i.
j.
!
A
Essay Questions. Use complete English sentences and proper grammar. If a question has multiple parts, you must answer
all of them to receive full credit. If you haven’t got a clue, leave it blank. If you are uncertain, put down
what you know, and indicate the things of which you are uncertain.
____ 26. (1 pt) How is a strong acid or base different from a weak acid or base?
____ 27. (1 pt) When a hydrocarbon is said to be saturated (like a fat), what does that mean?
____ 28. (1 pt) How do metal and nonmetal oxides react with water?
____ 29. (1 pt) What are functional groups?
____ 30. (1 pt) What is pH? How is the pH scale similar to the Richter scale (for earthquakes)?
3
A
Bonus Questions. The bonus questions are not obligatory, but will improve your score if you get them right. Use complete
English sentences and proper grammar. If a question has multiple parts, you must answer all of them to receive full credit. If
you haven’t got a clue, leave it blank. If you are uncertain, put down what you know, and indicate the things of which you are
uncertain.
____ B1. (1 pt) How do buffers work?
____ B2 (1 pt) What is the numerical value of Avogadro’s number and why is it so important to chemistry?
____ B3 (1 pt) What is a mole of a substance? How would you determine the mass necessary to have a mole of a
compound?
4
Name:
/25 pts
Quiz 05 2012 Su Answer Section
MULTIPLE CHOICE
1.
B
2.
E
3.
D
4.
C
5.
C
6.
B
7.
A
8.
A
9.
C
10. D
11.
E
MULTIPLE RESPONSE
12. A, B, C, D, E
13. A, B, D, E
14. B, C, E
15. A, E
MATCHING
16. E
17.
A
18. A
19. G
20. J
21.
I
22. H
23. B
24. F
25. C
ESSAY
26. A strong acid or base is one that dissociates completely into ions in aqueous solution. A weak acid or base is
one that will only dissociate partially. In other words, a weak acid only makes some of its hydrogen ions available. It is this property that allows weak acids to serve as buffers, when combined with their conjugate bases.
A solution of a strong acid can be weakly acidic if only a small amount of acid is present in a large volume of
solution, but that is a property of the solution rather than of the acid.
27. Saturated hydrocarbons have only single C–C bonds, and all other bonding positions on the carbon atoms are
filled with hydrogen.
28. Metal oxides react with water to form bases, while non-metal oxides react with water to form acids.
29. Functional groups are covalently-bonded groups of atoms that form pieces of larger molecules. These groups
have specific chemical attributes, or chemical functions, hence the name.
30. pH is the negative logarithm of the hydrogen ion concentration. Both of these scales are logarithmic, meaning
that a difference of one unit signifies a 10-fold difference in what is being quantified.
31. A buffer comprises a weak acid and the conjugate base of that acid. If base is added to the solution, the acid
releases more hydrogen ions to compensate for the base. If extra acid is added, the conjugate base absorbs the
excess protons to maintain the pH.
32. Avogadro’s number is believed today to be 6.02 x 1023 atoms of an element or molecules of a compound. It is
important because it establishes the relationship between numbers of atoms or molecules, which we cannot
see or count, and masses of solids or volumes of liquids that we can easily determine in the lab.
33. A mole is one Avogadro’s number of atoms of an element or molecules of a compound. One formula mass of
a compound, in grams, contains one Avogadro’s number of molecules of that compound.
A