( Re-generate )

Grade Distribution
0	2
20	3
40	7
60	20
80	38
100	46
A buffer is composed of (-1) no answer (1) a conjugate acid/base pair (2) aspirin (3) protonated acid (4) protonated base
-1	0
1	25
2	0
3	0
4	0
The quantity Ka is (-1) no answer (1) invariant with temperature (2) related to molecular weight of hydrocarbons (3) a measure of the strength of an acid (4) all of these are correct
-1	0
1	1
2	0
3	17
4	4
In a titration of a weak acid by a strong base (-1) no answer (1) two equivalents of base are always needed to neutralize all the acid present (2) the equivalence point cannot be defined exactly (3) there is a region in which the pH changes slowly (4) the equivalence point depends on the nature of the added base
-1	0
1	0
2	0
3	14
4	4
A buffer solution (-1) no answer (1) is used to control the pH of a solution (2) contains at least 100 times more of a weak acid than its conjugate base (3) contains at least 100 times less of a weak acid than its conjugate base (4) always has a pH of 7
-1	0
1	31
2	0
3	0
4	0
Buffering capacity refers to (-1) no answer (1) the effectiveness of commercial antacids (2) the extent to which a buffer solution can counteract the effect of added acid or base (3) the pH of a buffer solution (4) the molecular weight of the substance used as a buffer
-1	0
1	0
2	19
3	1
4	0
The main intracellular buffer system is (-1) no answer (1) H3PO4/H2PO4- (2) H2PO4-/HPO42- (3) HPO42-/PO43- (4) H3PO4/PO43-
-1	0
1	2
2	29
3	1
4	1
Which substance would be a suitable buffer at pH 5.0? (-1) no answer (1) one with a pka of 3.8 (2) one with a pka of 4.8 (3) one with a pka of 6.5 (4) one with a pka of 8.0
-1	0
1	3
2	28
3	1
4	1
Which of the following acids would serve as a good buffer for a chemical reaction at pH = 8? (-1) no answer (1) acetic acid (Ka = 1.76 X 10-5) (2) H2PO4- (Ka = 6.31 X 10-8) (3) bicarbonate (Ka = 5.6 X 10-11) (4) TRIS (Ka = 5.0 X 10-9)
-1	0
1	4
2	5
3	1
4	16
The ratio of a weak acid and its conjugate base at the point of maximum buffering capacity is (-1) no answer (1) 1/1 (2) 1/10 (3) 10/1 (4) no definite ratio can be calculated
-1	0
1	12
2	0
3	1
4	7
The dissociation constant for an acid with a pKa value of 5.60 is (-1) no answer (1) 9.0 X 10-6 (2) 5.0 X 10-6 (3) 1.0 X 10-6 (4) 2.5 X 10-6
-1	0
1	1
2	3
3	2
4	27
A buffer solution at pH 5.0 has a ratio of [HA]/[A-] of 10. What is the pKa of the acid? (-1) no answer (1) 4.0 (2) 5.0 (3) 7.0 (4) 6.0
-1	0
1	6
2	3
3	0
4	17
What is the pH of a phosphate solution made by the addition of 2.5 equivalents of NaOH to an initial solution of phosphoric acid? The pKa values are pKa1 = 2.12, pKa2 = 7.20, pKa3 = 12.40. (-1) no answer (1) 7.4 (2) 10.6 (3) 12.4 (4) 8.8
-1	0
1	6
2	7
3	12
4	4
A buffer with a pKa of 6.0 is at a pH of 5.0. What is the ratio of [A-] to [HA]? (-1) no answer (1) 100 (2) 10 (3) 0.1 (4) 0.01
-1	0
1	2
2	3
3	21
4	0
The amphipathic molecule in the list below is (-1) no answer (1) sodium chloride (2) acetic acid (3) benzene (4) oleic acid
-1	0
1	0
2	8
3	4
4	17
Ionic compounds and polar covalent compounds tend to dissolve in water because of (-1) no answer (1) ion-dipole and dipole-dipole interactions (2) dipole-induced dipole interactions (3) van der Waals bonds (4) hydrophobic interactions
-1	0
1	17
2	4
3	0
4	0
The substance most likely to form a micelle is (-1) no answer (1) acetic acid (2) sodium oleate (3) methyl alcohol (4) acetone
-1	1
1	1
2	24
3	3
4	2
Polar molecules are usually (-1) no answer (1) hydrophobic. (2) hydrophillic. (3) not found in living cells. (4) only found in polar bears.
-1	0
1	0
2	33
3	0
4	0
The physical properties of water are due to (-1) no answer (1) electrostatic interactions (2) covalent interactions (3) van der Waals interactions (4) all of these are correct
-1	0
1	0
2	0
3	1
4	13
The non-covalent interaction below associated with the strongest force in aqueous solution is (-1) no answer (1) dipole-induced dipole (2) hydrophobic interactions (3) hydrogen bonding (4) van der Waals forces
-1	0
1	0
2	2
3	18
4	0
Many of the properties of water can be accounted for by the fact that (-1) no answer (1) it is polar (2) it forms hydrogen bonds (3) it is a bent molecule (4) all of these are applicable
-1	0
1	2
2	1
3	0
4	13
Which of the following solutes can be expected to be involved in hydrogen bonds with solvent water? (-1) no answer (1) amines and alcohols only (2) alcohols and ketones only (3) amines and ketones only (4) amines, alcohols, and ketones
-1	0
1	0
2	3
3	0
4	9
Hydrogen bonds (-1) no answer (1) play an important role in the solvent properties of water (2) are not involved in protein structure (3) play a role in the properties of DNA, but but not of RNA (4) give water a lower boiling point than expected
-1	0
1	23
2	0
3	0
4	0
The correct order for the electronegativity of the elements listed below is (-1) no answer (1) O > N > S > C > H. (2) O > N > S > C > F. (3) H > C > S > N > O. (4) S > N > O > C > H.
-1	0
1	12
2	1
3	1
4	1
In a hydrogen bond (-1) no answer (1) three atoms lie in a straight line (2) there is stronger bonding than in a covalent bond (3) unpaired electrons play no role (4) none of these are correct
-1	0
1	7
2	1
3	0
4	6

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