AP CHEM Unit 6 Day 1 Review

When the chemical reaction A + B ⇄ C + D is at equilibrium, 
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• all four concentrations are equal.
• the reverse reaction has stopped. 
• the forward reaction has stopped.
• neither the forward nor the reverse reactions have stopped.

Write the general equilibrium constant for
2 NaBr(aq) + Pb(ClO₄)₂(aq) ⇄ PbBr₂(s) + 2 NaClO₄(aq)
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Write the equilibrium expression for the reaction
SbCl₅(g) ⇄ SbCl₃(g) + Cl₂(g)
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Write the reaction quotient for
Li₂CO₃(s) ⇄ Li₂O(s) + CO₂(g)
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I understand that there is a difference when writing a K_c vs a K_p expression in terms of notation. While K_c uses brackets, [ ], it would be INCORRECT to write a K_p expression using brackets.

• Yes, of course, I understand. I love chemistry.
• No. What? I love physics. 
• #chem4eva
• #phys4neva

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. 

For the reaction
CO(g) + 2 H₂(g) ⇄ CH₃OH(g)
∆G ◦ rxn = 21.1 kJ/mol at 225◦C. If you have a mixture with a P_CO=0.1 atm, P_H2=0.1 atm, and P_CH3OH=1 atm in a container at 225◦C, which of the following is true?
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• the reaction is at equilibrium
• the reaction will move toward the reactants to reach equilibrium.
• the mixture can never achieve equilibrium. 
• the reaction will move toward the products to reach equilibrium.

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• 0.36