Reversible Reactions and Equilibria

Question 1

What is a reversible reaction?

Answer 1

a reaction that can go both ways using the symbol ⇌. both forwards and backwards reactions go at different rates

Question 2

What is equilibrium?

Answer 2

when the rate of both reactions are at a constant speed and the concentrations of reactants and products don’t change anymore.

both reactions are still happening but cancel each other out

Question 3

What is the position of equilibrium?

Answer 3

the concentration of reactants and products at equilibrium

when there are more products than reactants, the position of equilibrium lies to the right

when there are more reactants than products, the position of equilibrium lies to the left

the position can change depending on the conditions

Question 4

What conditions are needed for equilibrium to take place?

Answer 4

only when in a sealed container so that no reactants or products can escape

Question 4

Describe the reaction for producing ammonium chloride?

Answer 4

. endo
NH3 + HCl ⇌ NH4Cl
exo

neutralisation reaction

1. in a glass tube put HCl on the left and NH3 on the right
2. a white solid will form (NH4Cl)

because HCl is heavier (higher Mr) is moves slower and NH3 moves faster. so the white solid will form closer to the left. (equilibrium position)

Question 5

How is the reaction of producing ammonium chloride reversible?

Answer 5

HCl + NH3 can be put together to form NH4Cl

but NH4Cl can be heated up and broken down back into HCl + NH3

Question 6

Describe the reaction of hydrated copper sulfate and how is it reversible?

Answer 6

. endo
CuSO4*5H20 ⇌ CuSO4 + 5H20
exo

can be hydrated by adding water

can be dehydrated by heating and evaporating water

Question 7

What is Le Chetalier principle?

Answer 7

for a system and dynamic equilibrium , the equilibrium will shift in order to oppose any external change.

Question 8

What is the effect of temperature on the Le Chetalier principle?

Answer 8

an increase in temperature shifts the equilibrium position in the direction of the endothermic reaction
- to use up the heat released to decrease the temperature

a decrease in temperature shifts the equilibrium position in the direction of the exothermic reaction
- to crate more heat to increase the temperature

Question 9

What is a catalyst and why don’t they affect equilibrium?

Answer 9

a substance that speeds up chemical reactions. in reversible reactions the catalyst speeds up both forward and backward reactions to the same extent. therefore they still stay at equilibrium because the rate of both reactions are still equal.