AP Chem Unit 06 Quiz POTENTIAL

Write the general equilibrium constant for
2 NaBr(aq) + Pb(ClO₄)₂(aq) ⇄ PbBr₂(s) + 2 NaClO₄(aq)
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• 1
• 2
• 3
• 4

Which of the following is TRUE? 
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• A large value of K means that the equilibrium concentrations of products are large compared to the equilibrium concentrations of the reactants.
• When the value of K is small, the equilibrium lies on the product side of the equilibrium reaction.
• When the value of K is large, the equilibrium lies on the reactant side of the equilibrium reaction.
• A small value of K means that the equilibrium concentrations of the reactants are small compared to the equilibrium concentrations of the products.

In which of the following cases will the LEAST time be required to arrive at equilibrium? K below refers to the equilibrium constant
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• K is a very large number.
• Cannot tell since the time to arrive at equilibrium does not depend on K.
• K is about 1. 
• K is a very small number. 

Suppose the reaction
A + 3 B → 2 C
has a value of K = 10.0 at a certain temperature. If 0.5 moles of A, 0.5 moles of B and 0.5 moles of C are placed in a 5 L solution, the reaction:
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• is at equilibrium.
• shifts to the left. 
• shift cannot be determined without the temperature. 
• shifts to the right. 

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•  1.1
• 0.60
• 1.7
• 0.36

The reaction for the synthesis of ammonia
N₂(g) + 3 H₂(g) → 2 NH₃(g)
is exothermic. Increasing the temperature applied to the system
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•  I and IV only
• I and III only
• II and IV only
• II and III only

Consider the reaction
Ni(s) + 4 CO(g) → Ni(CO)4(g)
At 30◦C and P_CO = 1 atm, Ni reacts with CO(g) to form Ni(CO)₄(g). At 200◦C, Ni(CO)₄(g) decomposes to Ni(s) and CO(g). This means
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• adding an inert gas like argon favors the forward reaction.
•  a decrease in pressure favors the forward reaction.
• K at 30◦C is greater than K at 200◦C
• the forward reaction is endothermic.

A 1.00 L vessel at 400◦C contains the equilibrium concentrations [NO]=0.1M, [CO₂]=0.02M, [NO₂]=0.01M, and [CO]=0.1M. What is the equilibrium constant for the reaction
NO₂(g) + CO(g) ⇄ NO(g) + CO₂(g) ?
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• 2.0
• 5.0 
• 0.5
• 1.0

A mixture consisting of 0.250 M N₂(g) and 0.500 M H₂(g) reaches equilibrium according to the equation
N₂(g) + 3 H₂(g) ⇄ 2 NH₃(g)
At equilibrium, the concentration of ammonia is 0.150 M. Calculate the concentration of H₂(g) at equilibrium.
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• 0.150 M
• 0.275 M
• 0.425 M 
• 0.0750 M

K_c = 25 at some temperature for the reaction
H₂(g) + I₂(g) ⇄ 2 HI(g)
If 25.2 mol of HI are introduced into a 10.0 liter vessel, how many moles of I₂ are present at equilibrium?
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• 3.6 mol
• 5.4 mol 
• 1.8 mol 
• 7.2 mol