Effects of concentration, pressure and catalysts on equilibrium constants

Question 1

the only factor that can change Kc is

this means that Kc is constant at

Answer 1

temperature

constant at a given temperature

Question 2

when the concentration of one of the components is altered, there is an immediate change in the

Answer 2

reaction quotient, Qc

Question 3

Qc is

Answer 3

the mathematical relationship between the concentrations of the components

Question 4

when the concentration of one of the components is altered, then the Qc is no longer equal to Kc, so the equilibrium composition will……………….until the Qc and the Kc are……………….

Answer 4

the equilibrium composition will change until the Qc and the Kc are equal

Question 5

at equilibrium, Qc =

Answer 5

Qc = Kc

Question 6

the expression for Qc is

Answer 6

[C]c[D]d
Qc= ————–
[A]a[B]b

Question 7

a change in pressure on an equilibrium system at constant temperature will have……………………on the value of Kc and Kp

Answer 7

no effect

Question 8

if the partial pressure of only one of the component gases is changed, then the overall effect on Kp can be predicted in the same way as

Answer 8

you would predict the change on Kc when a concentration is changed

Question 9

if the total pressure of a gaseous system is suddenly increased or decreased, then the partial pressures of all the gases will

Answer 9

either increase or decrease

Question 10

explain the effect of doubling the total pressure of the equilibrium system:

N2(g) + 3H2(g) = 2NH3(g)

Answer 10

N2(g) + 3H2(g) = 2NH3(g)

so Kp = (P NH3)2 / (PN2) (PH2)3

if the partial pressures of NH3= c , N2= a and H2= b
then:
Kp = c2 / ab3
so if the total pressure is doubled,
Qp = (2c)2 / 2a x (2b)3
so
(2c)2
Qp = ————
4ab3
now Qp is a quarter of the value of Kp, so in order for equilibrium to be established, the numerator has to increase, and the denominator decrease.
therefore, more nitrogen and hydrogen will react to form more ammonia, so producing more product and shifting the equilibrium position to the right