C13 Equilibrium

Question 1

Describe what happens at dynamic equilibrium

Answer 1

• The rate of forward and backwards reaction are equal so overall the amount of reactants and products are constant (NOT NECESSARILY EQUAL) as long as the ratio of reactants and products are constant

Question 2

What happens if you decrease the concentration of the product to the right of the equation in a reversible reaction

Answer 2

Favours forward reaction

Question 3

What happens if you increase the concentration of the product to the right of the equation in a reversible reaction and why

Answer 3

• Favours the reverse reaction
• Opposes the change by making more reactant due to an increased frequency of collisions in the product. This leads to more product being used up and more reactant being produced

Question 4

What happens if you decrease the concentration of the reactant to the right of the equation in a reversible reaction and why

Answer 4

• Favours the forward reaction
• Opposes the change by making less product to the left due to an decreased frequency of collisions in the right side of the equation. This leads to less reactant on the right being used up and less to the left being produced. The system try’s to balance out the equation.

Question 5

What happens if you increase the concentration of the reactant to the right of the equation in a reversible reaction and why

Answer 5

• Favours the reverse reaction
• Opposes the change by making more product due to an increased frequency of collisions on the right side of the equation. This leads to more reactant to the right being used up and more product being produced in order for the system to balance concentration.

Question 6

What happens in a reversible reaction when you increase the temperature of surroundings and why

Answer 6

• Favours the endothermic reaction
• System tries to counteract the change in surroundings by favouring the endothermic reaction so temperature decreases and returns to original

Question 7

What happens in a reversible reaction when you decrease the temperature of surroundings and why

Answer 7

• Favours the exothermic reaction
• System tries to counteract the change in surroundings by favouring the exothermic reaction so temperature increases and returns to original

Question 8

What happens in a reversible reaction when you increase the pressure and why

Answer 8

• Favours the reaction that results in fewer molecules
• System tries to counteract the change in surroundings by favouring the reaction that results in fewer molecules so the pressure decreases again

Question 9

What happens in a reversible reaction when you increase the pressure and why

Answer 9

• Favours the reaction that results in more molecules
• System tries to counteract the change in surroundings by favouring the reaction that results in more molecules so the pressure increases again

Question 10

Is the forward reaction in the Haber process endo/exo thermic

Answer 10

Exothermic

Question 11

Name 3 conditions used in the manufacturing of ammonia in the Haber process

Answer 11

• Pressure 200 atmospheres
• Temperature 450 degrees celsius
• Iron Catalysts

Question 12

Why does the Haber process run at 200 atmospheres

Answer 12

Higher pressure results in faster reaction times and increased ammonia yield however they cannot go higher as high pressure conditions are hard to maintain and unsafe

Question 13

Why does the Haber process run at 450 degrees celsius

Answer 13

Lower temperatures favour a higher yield of ammonia however if temperature is too low rate of reaction is too slow for industrial production

Question 14

Why is an iron catalyst used in the Haber process

Answer 14

Lowers activation energy of forward reaction to produce more ammonia with less energy required which makes the process more energy efficient

Question 15

What is Le Châtelier’s principal?

Answer 15

In a closed system if the conditions of a reversible reaction are altered, the closed system will counteract the change by favouring either the forward or backward reaction