Chemistry: Kc Calculations

Question 1

What equation is used to calculate Kc?

Answer 1

[products]^number of / [reactants]^number of

Question 2

Show how the Kc equation is applied to NH3 and its reversible reaction

Answer 2

N2 + 3H2 <—> 2NH3
therefore
Kc= [NH3]^2 / [N2] x [H2]^3

Question 3

What is the unit for concentration?

Answer 3

moldm-3

Question 4

How do you calculate Kc units from concentration units using the example of NH3?

Answer 4

[NH3]^2 / [N2] x [H2]^3 -> [moldm-3]^2 / [moldm-3] x [moldm-3]^3
-> 1 / [moldm-3]^2 -> mol-2dm6

Question 5

What does the Kc value change with?

Answer 5

temperature

Question 6

What values are used to calculate Kc?

Answer 6

concentration moldm-3

Question 7

How do we calculate Kc for an equilibrium using 2A + B2 <—> 2AB
where:
A= 0.0200 moldm-3
B= 0.100 moldm-3
AB= 0.400 moldm-3

Answer 7

[AB]^2 / [A]^2 x [B] -> [0.400]^2 / [0.0200]^2 x [0.100] = 400 mol-1dm3

Question 8

How does decreasing temperature in an endothermic reaction effect Kc?

Answer 8

decrease

Question 9

How does increasing the temperature of an endothermic reaction effect Kc?

Answer 9

increase

Question 10

How does increasing the temperature of an exothermic reaction effect Kc?

Answer 10

decrease

Question 11

How does decreasing temperature of an exothermic reaction effect Kc?

Answer 11

increase