Use the information below to answer the following quesitons: T he equilibrium co

Question

Use the information below to answer the following quesitons:

The equilibrium constant (K) of the reaction below is K = 6.0 X 10-2, with initial concentration as follows: [H2] = 1.0 x 10-2M, [N2] = 4.0 M, and [NH3] = 1.0 x 10-4M

a.) If the concentration of the reactant H2 was increased from 1.0 x 10-2 M to   2.5 x 10-1M, calculate the reaction quotient (Q) and determine which way the equilibrium position would shift.

b.) If the concentration of the reactant H2 was decreased from 1.0 x 10-2 M to   2.7 x 10-4M, calculate the reaction quotient (Q) and determine which way the equilibrium position would shift.

c.) If the concentration of the product NH3 was decreased from 1.0 x 10-4 M to 5.6 x 10-3M, calculate the reaction quotient (Q) and determine which way the equilibrium position would shift.

Explanation / Answer

K = 6*10^-2

Initial concentration

[H2] = 1.0 *10^-2 M

[N2] = 4.0 M

[NH3] = 1.0*10^-4 M

N2 + 3H2 <-> 2NH3

a)

If Reactant H2 is increased from 10^-2 tp 2.5*10^-1

Equilibrium expression

K = [NH3]^2/[H2]^3[N2]

Q = [NH3]^2/[H2]^3[N2] = (10^-4)^2 / (2.5*10^-1) /(4) = 1*10^-8

Recall that

If K < Q, there are more products than reactants. To decrease the amount of products, the reaction will shift to the left and produce more reactants

If K = Q; there is equilibrium

If K > Q, there are more products than reactants. To decrease the amount of products, the reaction will shift to the left and produce more reactants. For Q>K:

b)

If H2 is decreased

Q = [NH3]^2/[H2]^3[N2] = (10^-4)^2 / (2.7*10^-4) /(4) = 9.25*10-6

Once again, Q<K

If Q<K, there are more reactants than products. As a result, some of the reactants will become products, causing the reaction to shift to the right.

c)

If NH3 is decreased

Q = [NH3]^2/[H2]^3[N2] = (5.6*10^-3)^2 / (1*10^-2) /(4) = 0.000784 or 7.8*10^-4

Q is still less than K

If Q<K, there are more reactants than products. As a result, some of the reactants will become products, causing the reaction to shift to the right.

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