C7 Equilibria

Question 1

Properties of dynamic equilibrium

Answer 1

1. rate of forward reaction = rate of reverse reaction
2. conc. of products and reactants remain constant
3. in a closed system

Question 2

graphs of equilibrium

Answer 2

1. rate of reaction vs. time (visualise)
2. conc. vs time (visualise)

Question 3

Le Chatelier’s principle

Answer 3

if a change is made to a system at dynamic equilibrium, position of equilibrium moves to minimise this change

Question 4

factors affecting equilibrium position

Answer 4

1. concentration
2. pressure
3. temperature

Question 5

What are equilibrium constants affected by?

Answer 5

ONLY temperature

Question 6

Kc and Kp are in terms of…

Answer 6

Kc: concentration (moldm-3)
Kp: partial pressure (Pa/kPa/atm)

Question 7

Kc and Kp do not include…

Answer 7

Kc: DON’T include solids
Kp: ONLY include gases

Question 8

how to get partial pressure from number of moles?

Answer 8

mole fraction = no. of moles of gas/total moles of gas

partial pressure = mole fraction x total pressure

Question 9

how does temperature affect Kc and Kp?

Answer 9

exothermic (OPPOSITE):
temp increases, Kc/Kp decreases
temp decreases, Kc/Kp increases

endothermic (SAME):
temp increases, Kc/Kp increases
temp decreases, Kc/Kp decreases

Question 10

Bronsted-Lowry acid (strong/weak)

Answer 10

a proton donor

strong: that ionises completely in aqueous solution

weak: that ionises partially in aqueous solution

Question 11

Bronsted-Lowry base (strong/weak)

Answer 11

a proton acceptor

strong: that ionises completely in aqueous solution

weak: that ionises partially in aqueous solution

Question 12

titration curves
(strong acid-strong base)
(weak acid-strong bsae)
(strong acid-weak base)
(weak acid-weak base)

Answer 12

weak acid: starts a bit above pH 2
strong acid: starts a bit below pH 2

weak base: ends ~pH 10
strong base: ends ~pH 14