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Dr. Wang Chemistry 210, Fall 2006 Mock Examination II
- The โ n (^) gas for the reaction I 2 (s) + 3XeF 2 (s) 2IF 3 (s) + 3Xe(g) is
(a) 1 (b) -1 (c) -3 (d) 3
- The equilibrium constant (Kc) for the following reaction is 0.28 at 900oC. A system at equilibrium has [CS 2 ]=0.120 M, [H 2 ] = 0.100 M and [CH 4 ] = 8.4x 10-5^ M. What is the [H 2 S]?
CS 2 (g) + 4H 2 (g) CH 4 (g) + 2H 2 S(g)
(a) 0.11 (b) 0.15 (c) 0.20 (d) 0.27 (e) 0.
- The equilibrium constant Kc for the following reaction at 1100oC is 6.8 x10^51. What is Kp?
B(s) + 3/2F 2 (g) BF 3 (g)
(a) 6.7 x10^48 (b) 6.0 x 10^49 (c) 6.4 x10^50 (d) 6.8 x10^51 (e) 7.7 x10^53
- For which of the following reactions is product formation favored by high pressure and high temperature? (1) CO(g) + 3H 2 (g) CH 4 (g) + H 2 O(g) โ H (^) rxn = -206.2 kJ
(2) CO 2 (g) + C(s) 2CO (g) โ Hrxn = +172.5 kJ
Hrxn Hrxn Hrxn
(3) H 2 (g) + I 2 (g) 2HI(g) โ = -9.4 kJ
(4) N 2 (g) + O 2 (g) 2NO(g) โ = +181 kJ
(5) N 2 (g) + 2O 2 (g) 2NO 2 (g) โ = +66.4 kJ
(a) 1 (b) 2 (c) 3 (d) 4 (e) 5
- If the temperature of the following reaction is lowered from 100oC to 50oC, in which direction will the reaction shift and how will this affect the value of the equilibrium constant?
H 2 O(g) + CO(g) H 2 (g) + CO 2 (g) + heat
(a) shift in forward direction, Kc will increase (b) shift in reverse direction, Kc will increase (c) shift in forward direction, Kc will decrease (d) shift in reverse direction, Kc will decrease (e) shift in reverse direction, Kc will not change
- A mixture of 0.250 mol of NO, 0.750 mol of H 2 and 0.500 mol of N 2 is placed in a 1.00 L vessel and allowed to reach equilibrium. At equilibrium, the concentration of NO is 0.150 M. Calculate Kc for the reaction:
2NO(g) + 2H 2 (g) N 2 (g) + 2H 2 O(g)
(a) 0.00925 (b) 0.186 (c) 0.282 (d) 0.579 (e) 1.
- Which of the following will cause a change in the value of the equilibrium constant for a reaction? (a) addition of excess reactant (b) addition of excess product (c) addition of a catalyst (d) removal of product (e) changing the temperature
- If the pressure for the following reaction is increased, in which direction will the reaction shift and how will this affect the value of the equilibrium constant?
A (s) 2B(s)
(a) shift in forward direction, Kc will increase (b) shift in reverse direction, Kc will not change (c) shift in forward direction, Kc will decrease (d) shift in reverse direction, Kc will decrease (e) no shift, Kc will not change
- What is the pH of 0.0550M NaOH aqueous solution? (a) 1.26 (b) 2.90 (c) 11.1 (d) 7.00 (e) 12.
- What is the pH of a 0.42 M NH 4 Cl solution? (Ka=5.6x 10-10^ for the reaction NH 4 +^ (aq) NH 3 (aq) + H+(aq)) (a) 2.28 (b) 4.81 (c) 12.1 (d) 7.00 (e) 10.
- What is the pOH of 1.23x10-3^ M HCl?
(a) 11.09 (b) 2.91 (c) 12.86 (d) 5.
- Pyridine, C 5 H 5 N (Kb=1.5x10-9), is an organic base used in the synthesis of vitamins, drugs, and fungicides. Calculate the pH of the 0.3M C 5 H 5 N. (a) 4.67 (b) 9.33 (c) 5.85 (d) 10.
- Which of these statements is true regarding a 0.10M solution of a weak acid HA? (a) The pH is 1. (b) [H+]>> [A-] (c) [H+] = [A-] (d) The pH is less than 1.
20 .The conjugate acid-base pairs for the reaction: H 2 O(l) + CO 3 2-(aq) HCO 3 - (aq) + OH-^ (aq) are: (a) CO 3 2-/OH-^ and HCO 3 - / OH- (b) H 2 O/ OH-^ and HCO 3 - / CO 3 2- (c) HCO 3 - / CO 3 2-^ and HCO 3 - /H 2 O (d) HCO 3 - /H 2 O and CO 3 2-/ OH-
USEFUL INFORMATION
R = 8.314 J/mol K =0.08206 L atm/mol K
n gas K (^) p Kc RT = ( )โ
For a quadratic equation, ax^2 + bx + c =0, the solutions are
a
b b ac x 2
โ ยฑ^2 โ 4
Answer key is in the next page. DO NOT look at the answer key before you finish your work.
