This presentation shows you how to calculate the equilibrium constant for a reaction whose balanced equation has been multiplied by one half. It is of particular relevance to a certain past paper question. You will know the question that is being referred to by the time you complete the presentation.

1. CONSEQUENCES OF MULTIPLYING A BALANCED EQUATION
BY A CONSTANT
IN
CHEMICAL EQUILIBRIUM
FOR
CAPE UNIT 1 STUDENTS
(All content here applies to both Kc and Kp;
temperature being held constant.)
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2. YOU WILL LEARN
To find K when a balanced
equation is multiplied by any constant.
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3. FACT
“When a balanced equation is
multiplied by a factor, n, the
equilibrium constant is raised to that
factor, i.e. it becomes Kn”
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4. EXAMPLE
The value of the equilibrium constant for:
N2 + 3H2 ⇌ 2NH3
is K.
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5. 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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6. SOLUTION
For the reaction N2 + 3H2 ⇌ 2NH3
Kc = K = [NH3]2 * The superscript 1 is
[N2]1 [H2]3 included for clarity only.
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7. 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
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8. 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.
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9. EXTENDING THE CONCEPT
If the coefficients of the chemical equation are:
1. Doubled, the value of K is squared.
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10. 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.

11. 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.
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12. END
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