AP QUIZZES - AP TOPIC 13 Equilibrium SET B • AP Quizzes - AP TOPIC 13 Equilibrium SET B.

QUESTION 1. The reaction below has an equlibrium constant of 1000 at a given temperature.

2NO2(g) <==> N2O4(g)

What is the Kc for the reaction 2N2O4(g) <==> 4NO2(g)

(A) 1000
(B) 1.0 x 10-3
(C) 1.0 x 10-6
(D) 5.0 x 10-4
(E) 2000

QUESTION 2. Under what circumstances does Kp = Kc?

(A) Always
(B) When the number of moles of gaseous products are greater than the number of moles of gaseous reactants
(C) When the number of moles of gaseous products are less than the number of moles of gaseous reactants
(D) When the number of moles of gaseous products equal the number of moles of gaseous reactants
(E) Never

QUESTION 3. The decomposition of HF into its elements is found to have a Kc = 0.02. Starting with an initial amount of 0.20 mols of HF in a 10.0 L flask, how many moles of hydrogen gas will be present at equilibrium?

(A) 2.2
(B) 0.022
(C) 0.025
(D) 0
(E) 0.0025

QUESTION 4. A weak diprotic acid, H2X, is known to dissociate in two separate steps. The equilibrium constant for step 1 (the loss of one H+ ion) is known to be 1.4 x 10-4, the equilibrium constant for step 2 (the loss of the second proton from HX-) is known to be 8.9 x 10-8. What is the equilibrium constant for the reaction below?

H2X <==> 2H+ + X-

(A) 1573
(B) 6.36 x 10-4
(C) 1.40 x 10-4
(D) 1.25 x 10-11
(E) None of the above

QUESTION 5. When a solution of Cu (II) ions are mixed with a concentrated ammonia solution an equilibrium is set up according to the equation below. The complex ion formed is royal blue in color. Which operation would have the effect of decreasing the intensity of the blue coloration?

Cu2+(aq) + NH3(aq) <==> [Cu(NH3)4]2+(aq)

(A) Filtering the mixture
(B) Incresing the concentration of Cu (II) ions
(C) Adding more NH3
(D) Adding an ion that precipitates the Cu2+ out of solution
(E) Adding a catalyst 