Equilibrium Intro

Define chemical equilibrium.

• A reaction is reversible.
• The concentration of the reactants is equal to the concentration of the products.
• The rate of a forward reaction is equal to the rate of the reverse reaction.
• The reaction stops and no further change in concentration occurs.

What is the K_c expression for this reaction?
   2 NO_(g)  +  O_2(g) ⇌  2 NO_2(g)

• K_c = [NO₂]² / [NO]² [O₂]
• K_c =  [NO]² [O₂] / [NO₂]²
• K_c = [NO]² [O₂] [NO₂]²
• K_c = [NO₂]² / [NO]² +  [O₂]

What are [A] and [B]?

• concentration of reactants
• concentration of products
• energy of reactants
• energy of products

What is the equilibrium expression for:
Fe₃O₄(s) + 4H₂(g) <=> 3Fe(s) + 4H₂O(g)
K_c =

• [Fe]³ [H₂O]⁴  / [Fe₃O₄] [H₂]⁴
• [Fe₃O₄] [H₂]⁴ /  [Fe]³ [H₂O]⁴
• [H₂O]⁴ / [H₂]⁴
• [Fe] [H₂O] / [Fe₃O₄] [H₂]

At what time (in seconds) is equilibrium established?

• 0 seconds
• 1 second
• 5 seconds
• 10 seconds

Which of the following is NOT true at equilibrium?

• The forward and reverse reactions proceed at the same rate.
• The concentrations of reactants and products do not change.
• The concentration of the reactants is equal to the concentration of the products.
• The forward and reverse reactions continue to occur.

An equilibrium constant with a large magnitude indicates…

• A very fast reaction
• More products at equilibrium
• More reactants at equilibrium
• nothing, without considering the stoichiometry of the reaction

Why is equilibrium called a dynamic state?

• Chemists try to convert as much reactants as possible into products.

• Once equilibrium is achieved, the forward and reverse reactions do not stop.

• Once equilibrium is achieved, the forward and reverse reactions stop.

• All chemical reactions are considered to be reversible under suitable conditions.

If the reaction quotient Q has a smaller value than the related equilibrium constant, K, _________

• the reaction is at equilibrium

• the reaction is not at equilibrium, and will make more products at the expense of the reactants

• the reaction is not at equilibrium, and will make more reactants at the expense of the products

• the value of K will not increase until it is equal to Q

If the reaction quotient Q has a value larger than the related equilibrium constant, K _________

• the reaction is at equilibrium

• the reaction is not at equilibrium, and will make more products at the expense of reactants

• the reaction is not at equilibrium, and will make more reactants at the expense of products

• the value of K will increase until it is equal to Q