7.2 The Equilibrium Constant Kc

Question 1

What is the expression of the equilibrium constant for the reaction:
aA + bB —–> cC + dD

Answer 1

kc = ((C)^c(D)^d)/(A)^a(B)^b

where (A) represents the concentration of A at equilibrium. The products are always on the top of the fraction and reactants on the bottom. The coefficients of the species in the chemical equation become the powers of the concentrations in the equilibrium constant expression.

Question 2

What is important about Kc?

Answer 2

It is constant for a particular reaction at a particular temperature.

Question 3

How can the value of Kc be written the other way round?

Answer 3

Kc’ = 1/Kc

Question 4

What important informationdoes Kc provide for a reaction?

Answer 4

The equilibrium constant provides information about how far a reaction proceeds at a particular temperature.

Question 5

What does a large value of Kc suggest?

Answer 5

For a particular reaction the larger the value of the equilibrium constant the more the position of equilibrium lies towards the right.

Question 6

What does it mean if Kc»1?

Answer 6

The reaction proceeds alamos totally towards products.

Question 7

What does it mean if Kc«1?

Answer 7

The reaction hardly proceeds at all towards products.