Rates of Reaction

Question 1

Large k

Answer 1

fast rate of reaction

Question 2

Small k

Answer 2

slow rate of reaction

Question 3

When Kc > 1

Answer 3

The reaction favours products, equilibrium lies to right.

Question 4

When Kc

Answer 4

The reaction favours reactants, equilibrium lies to left.

Question 5

Effect on Kc when temperature increases (endothermic)

Answer 5

Kc increases. Equilibrium yield of products increases and equilibrium yield of reactants decrease.

Question 6

Effect on Kc when temperature increases (exothermic)

Answer 6

Kc decreases. Equilibrium yield of products decreases and equilibrium yield of reactants increase.

Question 7

Effect of temperature on k

Answer 7

k increases with an increase in temperature.

Question 8

Effect on Kc when increase in concentration of reactants

Answer 8

As concentration of reactants is increased the system is no longer in equilibrium so system increases products and decreases reactants. Kc remains unaltered.

Question 9

Effect on Kc when increase in concentration of products

Answer 9

As concentration of products is increased the system is no longer in equilibrium so system increases reactants and decreases products. Kc remains unaltered.

Question 10

Effect on Kc when pressure is increased

Answer 10

The concentration of the side with fewer gas moles increases, so the concentration of the side with more gas moles is increased to restore equilibrium. Kc remains unaltered.

Question 11

Compromise between Kc and k

Answer 11

At low temperatures there is a high yield but a slow rate of reaction. At high temperatures there is a low yield but fast rate of reaction. k needs to be increased enough for fast rate of reaction, without decreasing Kc and the yield too much.