chemical equilibrium

Question 1

What does a dynamic equilibrium mean

Answer 1

Occurs when the rate of the forward reaction equals the rate of reverse reaction and the concentration of reactants and products remain constant in a closed system

Question 2

Changing what factors alter the position of the equilibrium?

Answer 2

1. Concentration of reactant/product
2. Pressure
3. Temperature

Question 3

Explain Le Chatelier’s principle

Answer 3

If a system at equilibrium is disturbed, the equilibrium moves in the direction that tends to reduce the disturbance

Question 4

Explain what effect a catalyst has on the position of equilibrium

Answer 4

No effect because catalysts affect the rates of forward and reverse reactions equally

Question 5

What conditions affect the vale of Kc

Answer 5

Temperature

Question 6

Deduce the units for the value of Kc

Answer 6

mol-1 dm-3

Question 7

What does Kc being greater or less than 1 suggest for the position of equilibrium

Answer 7

Greater than 1 = to the right

Less than 1 = to the left

Question 8

What effect does decreasing the temperature of an endothermic reaction have on Kc

Answer 8

Kc decreases

Question 9

What effect does increasing the temperature of an endothermic reaction have on Kc

Answer 9

Kc increases

Question 10

What effect does increasing the temperature of an exothermic reaction have on Kc

Answer 10

Kc decreases

Question 11

What effect does decreasing the temperature of an exothermic reaction have on Kc

Answer 11

Kc increases

Question 12

When can a dynamic equilibrium occur?

Answer 12

In a closed system at a constant temperature

Question 13

Describe how increasing the concentration of a reactant affects Le Chataliers principle

Answer 13

If you increase the concentration of a reactant, the equilibrium will shift to the right in order to make more product to get rid of the extra reactant

Question 14

Describe how increasing the concentration of a product affects Le Chataliers principle

Answer 14

If you increase the concentration of the product, the equilibrium will shift to the left to remove the extra product by increasing the rate of the reaction

Question 15

Describe how pressure affects Le Chataliers principle

Answer 15

• Increasing the pressure shifts the equilibrium to the side with fewer gas molecules to reduce the pressure
• Decreasing the pressure shifts the equilibrium to the side with more gas molecules to raise the temperature

Question 16

Describe how temperature affects Le Chataliers principle

Answer 16

• Increasing temperature means adding heat, the equilibrium will shift in the endothermic direction to absorb the heat
• Decreasing the temperature removes heat, this will shift the equilibrium towards the exothermic direction to replace the heat