CONSEQUENCES OF MULTIPLYING A BALANCED EQUATION

BY A CONSTANT

IN

CHEMICAL EQUILIBRIUMFOR

CAPE UNIT 1 STUDENTS

(All content here applies to both Kc and Kp;

temperature being held constant.)Compiled By Denison At Global In Cunupia. 739-2656.

Compiled By Denison At Global In Cunupia. 739-2656.

YOU WILL LEARN

To find K when a balanced equation is multiplied by any constant.

Compiled By Denison At Global In Cunupia. 739-2656.

FACT

“When a balanced equation is multiplied by a factor, n, the

equilibrium constant is raised to that factor, i.e. it becomes Kn”

Compiled By Denison At Global In Cunupia. 739-2656.

EXAMPLE The value of the equilibrium constant for:

N2 + 3H2 ⇌ 2NH3

is K.

Compiled By Denison At Global In Cunupia. 739-2656.

EXAMPLE The value of the equilibrium constant for:

N2 + 3H2 ⇌ 2NH3

is K.

What is the value of the equilibrium constant for:

1/2N2 + 3/2H2 ⇌ NH3 ?

A. √K B. K/2 C. 2K D.K2

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SOLUTION For the reaction N2 + 3H2 ⇌ 2NH3

Kc = K = [NH3]2 * The superscript 1 is [N2]1 [H2]3 included for clarity only.

Compiled By Denison At Global In Cunupia. 739-2656.

SOLUTION For the reaction N2 + 3H2 ⇌ 2NH3

Kc = K = [NH3]2 * The superscript 1 is [N2]1 [H2]3 included for clarity only.

And for the reaction 1/2N2 + 3/2H2 ⇌ NH3

K’c = [NH3]1

[N2]1/2 [H2]3/2

Compiled By Denison At Global In Cunupia. 739-2656.

SOLUTION For the reaction N2 + 3H2 ⇌ 2NH3

Kc = K = [NH3]2 * The superscript 1 is [N2]1 [H2]3 included for clarity only.

And for the reaction 1/2N2 + 3/2H2 ⇌ NH3

K’c = [NH3]1

[N2]1/2 [H2]3/2

and you can see that: K’c2 = Kc = K, so K’c = √K.

Compiled By Denison At Global In Cunupia. 739-2656.

EXTENDING THE CONCEPT If the coefficients of the chemical equation are:

1. Doubled, the value of K is squared.

Compiled By Denison At Global In Cunupia. 739-2656.

EXTENDING THE CONCEPT If the coefficients of the chemical equation are:

1. Doubled, the value of K is squared.2. Halved, the value of K is replaced by its square root.

Compiled By Denison At Global In Cunupia. 739-2656.

EXTENDING THE CONCEPT If the coefficients of the chemical equation are:

1. Doubled, the value of K is squared.2. Halved, the value of K is replaced by its square root.3. Multiplied by n, the value of K is raised to the nth power.

Compiled By Denison At Global In Cunupia. 739-2656.

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