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Section 1: Equilibrium: A State of Dynamic Balance

Equilibrium: A State of Dynamic Balance


1.	What is the equilibrium constant expression for the following reaction? ClNO₂ + NO ‹–› NO₂ + ClNO Need a Hint?
		A)	K_eq = [ClNO₂][NO]/[NO₂][ClNO]
		B)	K_eq = [ClNO₂][ClNO]/[NO][NO₂]
		C)	K_eq = [NO]²[ClNO]/[ClNO]²[NO]
		D)	K_eq = [NO₂][ClNO]/[ClNO₂][NO]


2.	What is the equilibrium constant expression for the following reaction? H₂ + I₂ ‹–› 2HI Need a Hint?
		A)	K_eq = [HI]²/[H₂][I₂]
		B)	K_eq = [H₂][I₂]/ [HI]²
		C)	K_eq = [HI]²/[H]²[I]²
		D)	K_eq = [2HI]/ /[H₂][I₂]


3.	What is the equilibrium constant expression for the following reaction? PCl₅ ‹–› PCl₃ + Cl₂ Need a Hint?
		A)	K_eq = [PCl]⁵/[PCl]³[Cl]²
		B)	K_eq = [PCl₅]/[PCl₃][Cl₂]
		C)	K_eq = [PCl]³[Cl]²/[PCl]⁵
		D)	K_eq = [PCl₃][Cl₂]/ [PCl₅]


4.	What is the equilibrium constant expression for the following reaction? 2SO₃ ‹–› 2SO₂ + O₂ Need a Hint?
		A)	K_eq = [SO₂]²[O₂]/[SO₃]²
		B)	K_eq = [2SO₂][2O]/[2SO₃]
		C)	K_eq = 2[SO₂]²[O₂]/2[SO₃]
		D)	K_eq = [SO₃]²/[SO₂]²[O₂]


5.	What is the equilibrium constant expression for the following reaction? N₂ + 3H₂ ‹–› 2NH₃ Need a Hint?
		A)	K_eq = [N₂][H₂]³/[NH₃]²
		B)	K_eq = [N₂]³[H₂]/2[NH₃]
		C)	K_eq = [NH₃]²/[N₂][H₂]³
		D)	K_eq = 2[NH₃]/ [N₂]³[H₂]


6.	When Δ G is zero, ______________. Need a Hint?
		A)	the reaction is spontaneous
		B)	the reaction is not spontaneous
		C)	the reaction is at equilibrium
		D)	the reaction has no energy


7.	When the system A + B ↔ C + D is at equilibrium, ___________. Need a Hint?
		A)	the forward reaction has stopped
		B)	the reverse reaction has stopped
		C)	both the forward and reverse reactions have stopped
		D)	neither the forward nor the reverse reaction has stopped


8.	A molecular system that is a dynamic process with two opposing reactions balancing each other is a(n) ___________. Need a Hint?
		A)	chemical equilibrium
		B)	spontaneous reaction
		C)	nonspontaneous reaction
		D)	unreacted set of chemicals.


9.	What is the equilibrium constant expression for the following reaction? 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g) Need a Hint?
		A)	K_eq = [NH₃] [O₂]/[NO] [H₂O]
		B)	K_eq = [NH₃]⁴[O₂]⁵/[NO]⁴[H₂O]⁶
		C)	K_eq = [NO]⁴/[NH₃][O₂]
		D)	K_eq = [NO]²[H₄O]⁶/[NH₃]⁴[O₂]⁵


10.	What is the equilibrium constant expression for the following reaction? 2NH₄NO₃(s) → 2NH₃(g) + 2NO(g) + H₂(g) + 2O₂(g) Need a Hint?
		A)	K_eq = [NH₃][NO][H₂][O2]
		B)	K_eq = [NH₃]²[NO]²[H₂][O2]²
		C)	K_eq = ([NH₃][NO][H₂][O2])/[NH₄NO₃]
		D)	K_eq = ([NH₃]²[NO]²[H₂][O2]²)/[NH₄NO₃]²


11.	For the reaction, 2A + B → C + 2D at 35°C, the value of the forward rate constant, Kf, is 3.0 × 10^-3M^-1s^-1 and the value of the reverse rate constant, Kr, is 1.5 × 10^-2M^-2s^-1. Calculate the value of K_eq for this reaction. Need a Hint?
		A)	2
		B)	0.5
		C)	0.2
		D)	5


12.	Consider the following reaction in which all reactants and products are gases. 1.00 mole of A and 2.00 moles of B are placed in a 5.0—L container. After equilibrium has been established, 0.50 mole of D is present. What is the equilibrium constant for this reaction: A + 2B → 2C + D? Need a Hint?
		A)	1
		B)	0.15
		C)	0.33
		D)	3


13.	When will the least time be required for a reaction to reach equilibrium? Need a Hint?
		A)	K_eq is very small
		B)	K_eq is very large
		C)	K_eq is approximately 1.00
		D)	cannot tell because the time to reach equilibrium does not depend on K_eq