C8(b) Equilibria

Question 1

Define equilibrium

Answer 1

The point in a reversible reaction in which the forward and backward rates of reaction are the same
Therefore the amount of substances present in the reacting mixture remain constant

Question 2

Define dynamic equilibrium

Answer 2

If a reversible reaction is left in a closed system it eventually forms dynamic equilibrium
Dynamic = both forward and revers reactions are still happening
Equilibrium = amount of product and reactant remain the same - nb not usually equal concentration or amount

Question 3

Define closed system

Answer 3

A system in which no matter enters or leaves

Question 4

Define pressure

Answer 4

D

Question 5

Define concentration

Answer 5

D

Question 6

Define endothermic

Answer 6

A reaction that takes in energy from surroundings

Question 7

Define exothermic

Answer 7

A reaction that transfers energy to the surroundings

Question 8

Define yield

Answer 8

F

Question 9

Define equilibrium position

Answer 9

At equilibrium the rate of the forward reaction equals the rate of the reversible reaction

Question 10

What is a reversible reaction

Answer 10

The products can react together to reform reactants
The reaction is reversible
A+B<=>C+D
One reaction must be exothermic
The other must be endothermic
The energy transferred to surroundings is exactly same as energy transferred back when reaction goes in opposite direction

Question 11

What happens when hydrated copper sulphate is heated

Endo or exo

Answer 11

Blue solid turns white
Water produced
Anhydrous copper sulphate
CuSO4.5H2O <=> CuSO4+5H2O

Endothermic

Question 12

What happens when water is added to the anhydrous copper sulphate
Ends or exothermic

Answer 12

Hydrated copper sulphate
White solid turns blue

Exo

Question 13

What happens when you heat ammonium chloride

What is the process

Answer 13

Heat gently in test tube with loose mineral wool plug
Use clamp 
Test tube at an angle
Warm bottom of test tube
Wear eye protection

Question 14

What happens

Answer 14

Ammonium chloride breaks down into ammonia and hydrogen chloride gas
This is thermal decomposition
Gases rise in test tube as they cool they react again.
When it cools they recombine to form white solid ammonium chloride again
NH4Cl(s)<=>NH3(g) + HCl (g)