Chemical Equilibrium A2

Question 1

How does a reversible reaction approach equilibrium?

Answer 1

• initially the forwards reaction only occurs since there are only reactants
• soon, as more products are made, the reverse reaction occurs but only at a slow rate
• as more reactants are being used up and more products are being made (since the forwards reaction is occurring at a faster rate), the reverse reaction is increasing in rate
• this occurs until the rate of both reactions are the same and dynamic equilibrium is reached

Question 2

Rules of Dynamic Equilibrium?

Answer 2

• the rate of the forwards and backwards reactions are the same
• the concentration of both products and reactants is constant (NOT THE SAME)
• must be in a closed system

Question 3

What would happen if the concentration of the reactants increased in dynamic equilibrium?

Answer 3

• the equilibrium would shift to the right
• to remove the reactants by reacting them to form products
• to produce more products to increase their concentration

Question 4

What are the rules for the equilibrium position to change due to pressure?

Answer 4

• there needs to be at least 1 gas species
• there needs to be a different amount of molecules of products and reactants

Question 5

What happens if the total pressure is altered in a dynamic equilibrium and why?

Answer 5

• if the reaction has gas molecules, it will shift to the side with the least/most gas molecules depending on wether the reaction has increased or decreased in total pressure
• this is because the movement of gas molecules in a volume causes pressure, so removing or gaining gas molecules will decrease/increase pressure

Question 6

How will increasing the total pressure in a dynamic equilibrium affect it?

Answer 6

• by changing pressure, you change the concentration of any gas molecules which will change the rate of reaction

Question 7

What happens if the temperature is changed in a dynamic equilibrium?

Answer 7

• the equilibrium will shift depending on what the enthalpy change is
• if it’s negative, the forwards reaction is exothermic and vice versa
• so if temp is decreased, it will shift in the exothermic direction and vice versa
• it will also change the rate of reaction

Question 8

Catalyst effect on dynamic equilibrium?

Answer 8

• doesn’t affect the position of the equilibrium
• but speeds up overall rate of reaction and helps reach equilibrium faster

Question 9

Factors needed to be taken into consideration for industrial processes

Answer 9

• safety of workers
• cost
• rate of reaction
• good conditions of equilibrium for a good yield
• effects on environment
• availability of starting materials/reactants