3.17-3.22 Reversible reactions and equilibria

What do product molecules do in reversible reactions?

They react with each other or decompose and form reactant molecules again

What is the reversible symbol?

⇌

What does heating ammonium chloride produce?

Ammonia and hydrogen chloride gases

As ammonia and hydrogen chloride (g) cool down what do they recombine to form?

Solid ammonium chloride

What is water of crystallisation?

Water that is included in the structure of some salts during the crystallisation process

Which is endothermic and which is exothermic? Reversible reaction of hydrated copper sulfate to anhydrous copper sulfate.

Exothermic: adding water to create hdyrated copper sulfate
Endothermic: heating to create anhydrous copper sulfate

When is the overall reaction said to be in a state of equilibrium?

When the rate of the forward reaction equals the rate of the reverse reaction

Equilibrium is [ ]

Dynamic

In dynamic equilibrium, the concentration of reactants and products remains [ ]

Constant

Dynamic equilibrium can only happen in a…

Closed system

What does Le Chatelier’s Principle state?

When a change is made to the conditions of a system at equilibrium, the system automatically moves to oppose the change

When is Le Chatelier’s Principle used to predict changes to the position of equilibrium?

When there are changes in temperature or pressure

When the position of equilibrium is said to shift, when it goes to the left, what does that mean?

It means that the reverse reaction is favoured (think how you would write a chemical equation)

If the temperature increases, which direction will the equilibrium shift to?

To the direction of the endothermic reaction as chemical potential energy is being absorbed

In gaseous reactions, what will a decrease in pressure favour? What type of reaction? A reaction that…

A reaction that produces the greatest number of molecules (to try and increase the pressure back up following Le Chatelier’s Principle)

If there are equal moles of gases one either side of the equation, there is NO effect on the position of equilibrium when pressure is changed. Increasing the pressure will…

Increase the rate of forward and backward reaction equally so the position of equilibrium is unchanged

When the conditions at equilibrium are changed, the system always responds by doing the…

Opposite

What does the presence of a catalyst on equilibrium do?

The presence of a catalyst does not affect the position of equilibrium but it DOES increase the rate at which equilibrium is reached