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Chemistry 12 - Unit 4 Quiz



True/False
Indicate whether the sentence or statement is true or false.
 

1. 

At equilibrium, the concentrations of all reactants and products are equal.
 

2. 

Condensed phases, such as liquids, are omitted when writing equilibrium constant expressions.
 

3. 

For the following equilibrium,
2 NOCl(g)  c12-u4_files/i0040000.jpg  2 NO(g) + Cl2(g)      c12-u4_files/i0040001.jpgH° = +77.1 kJ
      the equilibrium concentration of chlorine can be increased by raising the temperature.
 

4. 

Catalysts generally favour the forward reaction in equilibrium.
 

5. 

Adding an inert gas, such as helium, to the following equilibrium system will increase the equilibrium concentration of carbon dioxide.
2 CO2(g)  c12-u4_files/i0060000.jpg  2 CO(g) + O2(g)
 

6. 

Consider the reaction:
2 HI(g)  c12-u4_files/i0070000.jpg  H2(g) + I2(g) + 52.8 kJ      K = 50 at 450°C 
      The value of the equilibrium constant will increase as the temperature increases.
 

7. 

Consider these solubility products:
            Compound            Ksp
            CaF2            3.9 c12-u4_files/i0080000.jpg 10-11
            AgCl            1.8 c12-u4_files/i0080001.jpg 10-10
      Based on this information, silver chloride is more soluble than calcium fluoride.
 

8. 

Silver chloride is less soluble in a solution of sodium chloride than in distilled water.
 

9. 

The activation energy for the forward and reverse reaction in an equilibrium system is always the same.
 

10. 

Exothermic reactions always occur spontaneously.
 

11. 

The pH of 0.1 mol/L acetic acid is 1.
 

12. 

Hypochlorite ion, ClO-(aq) (Ka = 3.4 c12-u4_files/i0130000.jpg 10-7) is a stronger base than ammonia, NH3(aq) (Kb = 1.8 c12-u4_files/i0130001.jpg 10-5).
 

13. 

Metal oxides form acidic solutions while nonmetal oxides form basic solutions.
 

14. 

Potassium sulfate, K2SO4(s), (a fertilizer) dissolves in water to form an acidic solution.
 

15. 

Ammonia, NH3(aq), may act as a Lewis base and a Brønsted–Lowry base.
 

16. 

The pH of a sulfurous acid solution, H2SO3(aq) (Ka1 = 1.2 c12-u4_files/i0170000.jpg 10-2; Ka2 = 6.6 c12-u4_files/i0170001.jpg 10-8), may be calculated from its Ka1 value only.
 

17. 

At the equivalence point of any titration, pH = 7.
 

18. 

Methyl orange (pKIn = 4) is a good indicator for strong acid–strong base titrations.
 

19. 

The highlighted portion of Figure 1 indicates the part of a titration where a buffering action occurs.
c12-u4_files/i0200000.jpg
Figure 1
 

20. 

Figure 2 is a curve for the titration of a weak base (sample) with a strong acid (titrant).
c12-u4_files/i0210000.jpg
Figure 2
 

21. 

An effective acid–base buffer contains approximately equal concentrations of a strong acid and its conjugate base.
 

22. 

An H2CO3(aq)/HCO3-(aq) buffer is one of several buffer systems used to control pH in blood.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

23. 

In the following reaction, the two Brønsted–Lowry acids are
HSO4c12-u4_files/i0250000.jpg(aq) + HSO3c12-u4_files/i0250001.jpg(aq)  c12-u4_files/i0250002.jpg H2SO3(aq) + SO42-(aq)
a.
HSO4c12-u4_files/i0250003.jpg(aq) and HSO3c12-u4_files/i0250004.jpg(aq)
b.
HSO4c12-u4_files/i0250005.jpg(aq) and H2SO3(aq)
c.
SO42-(aq) and H2SO3(aq)
d.
HSO3c12-u4_files/i0250006.jpg(aq) and H2SO3(aq)
e.
HSO3c12-u4_files/i0250007.jpg(aq) and SO42-(aq)
 

24. 

Which of the following can act as a Brønsted–Lowry acid and a Brønsted–Lowry base in water.
a.
NH3(aq)
b.
HPO42–(aq)
c.
OHc12-u4_files/i0260000.jpg(aq)
d.
HI(aq)
e.
NH2c12-u4_files/i0260001.jpg(aq)
 

25. 

If the [H+(aq)] in a solution is 2.0 c12-u4_files/i0270000.jpg 10-4 mol/L, the hydroxide ion concentration is
a.
5.0 c12-u4_files/i0270001.jpg 10-10 mol/L
b.
2.0 c12-u4_files/i0270002.jpg 10-4 mol/L
c.
5.0 c12-u4_files/i0270003.jpg 10-4 mol/L
d.
2.0 c12-u4_files/i0270004.jpg 10-11 mol/L
e.
5.0 c12-u4_files/i0270005.jpg 10-11 mol/L
 

26. 

The acid ionization constant for acetic acid, HC2H3O2(aq), is 1.8 c12-u4_files/i0280000.jpg 10-5. Which of the following is true of a 0.1 mol/L acetic acid solution?
a.
[H+(aq)][C2H3O2c12-u4_files/i0280001.jpg(aq)] > [HC2H3O2(aq)]
b.
[H+(aq)][C2H3O2c12-u4_files/i0280002.jpg(aq)] < [HC2H3O2(aq))]
c.
[H+(aq)][C2H3O2c12-u4_files/i0280003.jpg(aq)] = [HC2H3O2(aq)]
d.
[H+(aq)]  >  [C2H3O2c12-u4_files/i0280004.jpg(aq)]
e.
[H+(aq)] <  [C2H3O2c12-u4_files/i0280005.jpg(aq)]
 

27. 

Consider the acid ionization constants of the acids in Table 1.
Table 1      Acid Ionization Constants
Acid
Ka
HF(aq)
6.6 c12-u4_files/i0290000.jpg 10-4
HCO2H(aq)
1.8 c12-u4_files/i0290001.jpg 10-4
HC2H3O2(aq)
1.8 c12-u4_files/i0290002.jpg 10-5
HClO(aq)
2.9 c12-u4_files/i0290003.jpg 10-8
HCN(aq)
6.2 c12-u4_files/i0290004.jpg 10-10
      The correct order of increasing pH of a 0.1 mol/L solution of these acids is
a.
HCN(aq), HClO(aq), HC2H3O2(aq), HCO2H(aq), HF(aq)
b.
HF(aq), HCO2H(aq), HC2H3O2(aq), HClO(aq), HCN(aq)
c.
HCO2H(aq), HC2H3O2(aq), HClO(aq), HCN(aq), HF(aq)
d.
HF(aq), HCN(aq), HClO(aq), HCO2H(aq), HC2H3O2(aq)
e.
HCN(aq), HF(aq), HC2H3O2(aq), HCO2H(aq), HClO(aq)
 

28. 

Which of the following salts hydrolyzes to give a basic solution?
a.
KCl(s)
b.
AlCl3(s)
c.
Na2SO3(s)
d.
Na2SO4(s)
e.
CaCl2(s)
 

29. 

Which of the following salts hydrolyzes to give an acidic solution?
a.
KCl(s)
b.
AlCl3(s)
c.
Na2SO3(s)
d.
Na2SO4(s)
e.
CaCl2(s)
 

30. 

Which of the following salts produces a neutral solution when dissolved in water?
a.
Na2CO3(s)
b.
NH4Cl(s)
c.
Ba(OH)2(s)
d.
KHSO4(s)
e.
Ca(NO3)2(s)
 

31. 

Consider 0.1 mol/L aqueous solutions of the following compounds:
I      NaNO3(aq)      IV      Fe(NO3)3(aq)
II       Cr(NO3)3(aq)      V      Na3PO4(aq)
III      Al(NO3)3(aq)
In order of increasing pH, the solutions are:
a.
V, I, III, II, IV
b.
I, II, III, IV, V
c.
IV, II, III, I, V
d.
IV, II, III, V, I
e.
IV, III, II, I, V
 

32. 

The hydroxide ion concentration in a 1.0 mol/L solution of acetic acid at 25°C is
a.
4.2 c12-u4_files/i0340000.jpg 10-3 mol/L
b.
2.4 c12-u4_files/i0340001.jpg 10-11 mol/L
c.
2.4 c12-u4_files/i0340002.jpg 10-12 mol/L
d.
2.4 c12-u4_files/i0340003.jpg 10-3 mol/L
e.
1.8 c12-u4_files/i0340004.jpg 10-5 mol/L
 

33. 

Barium hydroxide completely dissociates in aqueous solution. What is the [OHc12-u4_files/i0350000.jpg(aq)] in a 0.5 mol/L solution of barium hydroxide?
a.
0.5 mol/L
b.
0.25 mol/L
c.
0.75 mol/L
d.
1.0 mol/L
e.
0.1 mol/L
 

34. 

Which of the following titrations has a pH of 9 at the equivalence point?
a.
hydrochloric acid and sodium hydroxide
b.
hydrochloric acid and ammonia
c.
acetic acid and sodium hydroxide
d.
nitric acid and ammonia
e.
acetic acid and ammonia
 
 
c12-u4_files/i0370000.jpg
Figure 3
 

35. 

The graph in Figure 3 is the titration curve of
a.
a strong monoprotic acid with a strong base
b.
a strong monoprotic acid with a weak base
c.
a weak monoprotic acid with a strong base
d.
a weak monoprotic acid with a weak base
e.
none of the above
 

36. 

The titration of a weak base with a strong acid results in a solution with pH
a.
equal to 7
b.
greater than 7
c.
less than 7
d.
equal to 14
e.
equal to 1
 

37. 

Phenolphthalein (abbrev. HPh) is an acid–base indicator commonly used during titrations. The colour changes observed in the titration are based on the following equilibrium
HPh(aq)  c12-u4_files/i0400000.jpg  H+(aq) +      Phc12-u4_files/i0400001.jpg(aq)
(colourless)                    (pink)
      During the titration of a strong acid sample with a strong base titrant, the colour of the sample
a.
changes from pink to colourless.
b.
changes from colourless to pink.
c.
remains colourless throughout.
d.
remains pink throughout.
e.
changes from pink to colourless then back to pink.
 

38. 

If the [H+(aq)] at the equivalence point is calculated to be 1.0 c12-u4_files/i0410000.jpg 10-4 mol/L for a particular titration, which of the following acid–base indicators should be used to mark the endpoint?
a.
methyl orange
b.
bromocresol green
c.
bromothymol blue
d.
phenol red
e.
phenolphthalein
 

39. 

Which of the following combinations of chemicals could form an effective buffer solution?
a.
HCl(aq) and KOH(aq)
b.
HF(aq) and HNO3(aq)
c.
NH3(aq) and NaOH(aq)
d.
HC2H3O2(aq) and C2H3O2c12-u4_files/i0420000.jpg(aq)
e.
NH4+(aq) and Brc12-u4_files/i0420001.jpg(aq)
 

40. 

A Lewis acid is
a.
a proton donor.
b.
a proton acceptor.
c.
an electron pair donor.
d.
an electron pair acceptor.
e.
both (a) and (d).
 

41. 

Identify the Lewis base
a.
H+(aq)
b.
SO3
c.
BeH2
d.
BH3
e.
O2-(aq)
 



 
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