Exam #3 Flashcards
(41 cards)
Which of the following statements best describes what occurs at equilibrium?
a.) the reaction has stopped so the concentrations of reactants and products do not change.
b.) the amount of products are equal to the amount of reactants.
c.) the rate of the reaction in the forward reaction equals the rate constant for the reverse reaction.
d.) the rate constant for the forward reaction equals the rate constant for the reverse reaction.
c.) the rate of the reaction in the forward reaction equals the rate constant for the reverse reaction.
Which of the following is the correct expression for the concentration based equilibrium constant for the reaction:
A(g) + 2B(g) ⇌ 3C(g)
a.) Kc = [C]^3/[A][B]^2
b.) Kc = [C]^3
c.) Kc = [A][B]^2/[C]^3
d.) [A][2B]/[3C]
a.) Kc = [C]^3/[A][B]^2
The Kp for the reaction A(g) ⇌ 2B(g) is 0.0450. What is Kp for the reaction 2A(g) ⇌ 4B(g)?
a.) -0.0450
b.) 0.0900
c.) 0.0225
d.) 0.00203
d.) 0.00203
Consider the reaction below:
2SO3(g) ⇌ 2SO2(g) + O2(g)
The Kp is 1.81 *10^-5 at 350 degrees C. Calculate the Kp at the same temperature. (R = 0.08314)
a.) 6.710^-4
b.) 0.052
c.) 3.4910^-7
d.) 0.40
c.) 3.49*10^-7
If the reaction quotient (Q) for a given reaction is less than the equilibrium constant (K) then
a.) the reaction will proceed in the forward direction
b.) the reaction will proceed in the reverse direction
c.) the reaction is at equilibrium
a.) the reaction will proceed in the forward direction
For a particular reaction K=98000. What can be said about this reaction?
a.) there are many more products than reactants in the equilibrium mixture.
b.) there are many more reactants than products in the equilibrium mixture.
c.) there are roughly equal amounts of reactants and products because K does not equal 1.
d.) the reaction has not yet reached equilibrium because K does not equal 1.
a.) there are many more products than reactants in the equilibrium mixture.
Consider the reaction: 2NO2(g) ⇌ N2O4(g)
At equilibrium, the partial pressures of N2O4 and NO2 are 0.35 atm and 4.3 atm, respectively. What is Kp?
a.) 0.019
b.) 0.146
c.) 0.0532
d.) 121
a.) 0.019
At 460 K, △G = -10.10 kJ/mol for the reaction 2A(g) -> B(g). If the partial pressures of A and B are 7.20 atm and 0.420 atm respectively, what is the △G for this reaction?
a.) 54 kJ/mol
b.) 8.32 kJ/mol
c.) -8.32 kJ/mol
d.) -54 kJ/mol
b.) 8.32 kJ/mol
Consider the following chemical reaction at equilibrium:
2NO2(g) ⇌ N2O4(g) △Hrxn < 0
If the temperature is increased by 20K while the pressure is kept constant, in which direction will the equilibrium shift?
a.) reactants
b.) products
c.) neither the reactants nor products
a.) reactants
Consider the following chemical reaction at equilibrium:
2NO2(g) ⇌ N2O4(g)
If the container’s volume is increased by a factor of 2, while temperature is kept constant, how will Keq for the reaction change?
a.) increase
b.) decrease
c.) stay the same
c.) stay the same
Consider the following chemical reaction at equilibrium:
CO(g) +H2O(g) ⇌ CO2(g) + H2(g)
If H2 is removed, how will Keq for the reaction change?
a.) increase
b.) decrease
c.) stay the same
c.) stay the same
Consider the following chemical reaction at equilibrium:
HF(aq) +H2O(l) ⇌ H3O+aq) + F-(aq)
If one drop of aqueous hydrochloric acid (HCl) is added, how will the Keq for the reaction change?
a.) increase
b.) decrease
c.) stay the same
c.) stay the same
A one mole sample of NOBr was placed in a 10 L container at 25 degrees C, and the following reaction was allowed to come to equilibrium.
2NOBr(g) ⇌ 2NO(g) + Br2(g)
The equilibrium concentrations were found to be [NOBr] = 0.0838 M, [NO] = 0.0162 M, and [Br2] = 0.00810 M. Calculate the Kc for the reaction.
a.) 9.55 10^-3
b.) 7.9410^-3
c.) 6.7 *10^-4
d.) 3.03 *10^-4
d.) 3.03 *10^-4
For the reaction
PCl5(g) ⇌ PCl3(g) + Cl2(g)
Kp = 1.45*1-^-4 at 160 C. A 1.00 L vessel at 160 C is filled with Pcl5(g) at an initial pressure of 3.75 atm and allowed to come to equilibrium. What will be the pressure (in atm) of Cl2(g) at equilibrium?
a.) 2.33 atm
b.) 0.00233 atm
c.) 0.0233 atm
d.) 23.3 atm
c.) 0.0233 atm
Determine the equilibrium constant for a reaction at 230 K if △G = -16.20 kJ/mol. (R = 8.314 J/mol K)
a.) 2.3410^-3
b.) 1.8510^-4
c.) 4.7810^3
d.) 1.7510^-4
c.) 4.78*10^3
Predict the conjugate acid of HCO2-.
a.) CO22-
b.) HCO2H2+
c.) HCO2
d.) HCO2H
d.) HCO2H
Ca(OH)2 is a Bronsted-Lowry base because
a.) it can dissolve in water
b.) it is a hydroxide donor
c.) it is a proton acceptor
d.) it is a polar molecule
c.) it is a proton acceptor
The concentration of hydroxide ion in an aqueous solution at 25 C is 3.6*10^-4 M. What is the concentration of the hydronium ion?
a.) 0.0055 M
b.) 0.0096 M
c.) 4.9 *10^-12 M
d.) 2.8 *10^-11 M
d.) 2.8 *10^-11 M
Consider the following reaction in the forward direction. Identify the base:
CH3O- + H2O ⇌ CH3OH + OH-
a.) CH3O-
b.) H2O
c.) CH3OH
d.) OH-
a.) CH3O-
Which of the following is a conjugate acid-base pair?
a.) OH-, H2O
b.) NH3, OH-
c.) OH-, NH4+
d.) H2O, NH4+
a.) OH-, H2O
Which of the following is an amphoteric species?
a.) H2S
b.) HS-
c.) S2-
b.) HS-
Calculate the pH of a 0.00040 M solution of HBr at 25 C.
a.) 6.80
b.) 3.40
c.) 2.10
d.) 0.95
b.) 3.40
A solution has a pH of 13.20. We can conclude that
a.) the solution is very acidic
b.) the solution is only slightly acidic
c.) the solution is only slightly basic
d.) the solution is very basic
d.) the solution is very basic
A solution has a pOH of 13.12. This tells us
a.) the solution is very acidic
b.) the solution is only slightly acidic
c.) the solution is only slightly basic
d.) the solution is very basic
a.) the solution is very acidic
