Chapter 10 Le Chateliers principle

Question 1

Characteristics of a chemical system at equilibrium 3

Answer 1

Must be a closed system
The rate of the forwards reaction=that of the reverse
The conc of reactants and products remain constant

Question 2

Harber process

Answer 2

Industrial process of manufacturing ammonia from hydrogen and nitrogen gases
Reversible reaction

Question 3

Dynamic equilibrium

Answer 3

Forward and reverse reactions occur at the same time to reach equilibrium

Question 4

Factors affecting position of equilibrium

Answer 4

Concentration/pressure
Temperature

Question 5

Does the presence of a catalyst affect equilibrium

Answer 5

No

Question 6

Affect of catalyst on a reversible reaction 2

Answer 6

Speeds up the rates of both the forwards and reverse reactions equally
Increases the rate at which equilibrium is established

Question 7

What would be the best conditions for the highest yield of ammonia in the harber process

Answer 7

Low temp
High pressure
Low concentration of products
All of these cause the forwards reaction to be favoured

Question 8

Temperature compromise in the harber process and reason

Answer 8

350-500°c
Though a low temp increases yield, it decreases RoR

Question 9

Pressure compromise in the harber process and why

Answer 9

100-200 atm
High pressure increases yield and RoR but would require a strong-walled reaction vessel and require more energy (increases cost)

Question 10

Why is ammonia removed as it is produced in the harber process. Why is this better than increasing conc of reactants

Answer 10

Removing ammonia as it forms decreases con of products, shifting equilibrium to the right.
Better than increasing conc of reactants as this would be more costly

Question 11

Conditions used in reality for the harber process

Answer 11

Iron catalyst
350-500°c
100-200 atm

Question 12

What does the magnitude of the equilibrium constant mean

Answer 12

The relative proportions of reactants and products in the equilibrium system (which side of the equation thr equilibrium is closer to)

Question 13

What does it mean if equilibrium constant =1

Answer 13

The position of equilibrium lies halfway between reactants and products so [reactants]=[products]

Question 14

What does it mean if the equilibrium constant is greater than 1

Answer 14

Equilibrium lies on the right of the equation so [products]>[reactants]

Question 15

What die sit mean if the equilibrium constant is less than 1

Answer 15

Equilibrium is on the left of the equation so [reactants]>[products]

Question 16

Generally a greater equilibrium constant means

Answer 16

Equilibrium lies further to the right

Question 17

What does [x] mean

Answer 17

‘The concentration of x’

Question 18

Symbol for equilibrium constant

Answer 18

K sub c

Question 19

Equation to find equilibrium constant

Answer 19

Product of the equilibrium concentration of products ÷ Product of the equilibrium concentration of reactants
Where the concentrations are to the power of their coefficient in the chemical equation

Question 20

Equilibrium concentrations?

Answer 20

The concentration of a product or reactant in a reversible reaction when the system is at equilibrium

Question 21

Equilibrium constant?

Answer 21

A value for the exact position of equilibrium in a reversible reaction