Dynamic equillibrium

Question 1

Dynamic equilibrium definition?

Answer 1

is the equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations do not change

Question 2

What is meant if a system is closed?

Answer 2

A system isolated from it’s surroundings, no material is added or removed, and conditions are changing

Question 3

4 characteristics of a dynamic equilibrium?

Answer 3

Exists in a closed system
Rate of forward reaction is equal to rate of reverse reaction
No overall change in concentrations
Can be approached from either side

Question 4

What does Le Chatelier’s Principle state?

Answer 4

when a system in dynamic equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium

Question 5

What would happen if you added more reactants to a reversible reaction?

Answer 5

Counteracts, by shifting to the right, more product is formed

Question 6

What happens if you take away the product formed in a reversible reaction?

Answer 6

Counteracts by shifting right, producing more product

Question 7

What does increasing the pressure in a reversible reaction do?

Answer 7

Shifts to the side which has less moles of gas

Question 8

What does adding a catalyst do to a reversible reaction?

Answer 8

Nothing both sides increase equally

Question 9

What happens if you increase the temperature in a reversible reaction?

Answer 9

If forward reaction is exothermic (negative), then shifts left
If forward reaction is endothermic (positive), then shifts right

Question 10

How do you find Kc the equilibrium constant?

Answer 10

aA + bB ⇌ cC + dD

then Kc = ([C]^c [D]^d)/([A]^a [B]^b)

Then input equilibrium concentration values into the equation

Question 11

How do you work out concentrations for Kc from a table?

Answer 11

Put mole values for what the products started at, and the products start at 0
Look at changes to see what must be done to each chemical, (number of moles is relevant) to work out the equilibrium moles
Work out the concentrations

Question 12

How to work out moles from mass and mr?

Answer 12

Moles = mass / mr

Question 13

How to work out moles from concentration and volume?

Answer 13

Moles = concentration x volume

Question 14

How to find the volume of a gas?

Answer 14

24dm^3 x moles = volume

Question 15

What does it mean if Kc is bigger than 1?

Answer 15

equilibrium lies far too the right

Question 16

What does it mean if Kc is smaller than 1?

Answer 16

Equilibrium lies far to the left

Question 17

How do you find units for Kc?

Answer 17

Cancel on top and bottom, and then put all together, if they cancel then there are no units

Question 18

What is homogenous equilibrium?

Answer 18

All products and reactants are in the same state

Question 19

What’s the ideal gas law?

Answer 19

PV = nRT

P= Pa
V= m^3
n= mol
R=  ideal gas constant, J mol^-1 K^-1
T= kelvin

Question 20

How do you find the partial pressure of a gas when given the amount of moles of every gas?

Answer 20

Work out what percent of the total moles the gas you’ve been asked for is, then work out what this is of the total pressure
(standard = 100kPa/ 1 atm

Question 21

Formula for Kp?

Answer 21

aA + bB ⇌ cC + dD

Kp = (p(C)^c p(D)^d)/(p(A)^a p(B)^b)

Find the partial pressures using the method when find what percent the moles are of the total moles, then multiplying by the total pressure

Units is Pa but can cancel out, treat as indices to work out if minus power or positive and what power it is to

Question 22

What’s the only factor which will affect the equilibrium constant?

Answer 22

Temperature

Question 23

Negatives of altering conditions to improve industrial production in equilibrium reactions?

Answer 23

Using high temp uses lot of energy/ fuel consumption
High pressure very costly as strong containers have to be made, and lots of energy used
Also dangerous as high pressure can lead to explosions

Question 24

Explain the compromise in the haber process?

Answer 24

Temperature is 450 degrees, which means high rate, as more frequent collsions, and greater proportion of particles have energy higher than the activation energy, so greater proportion of collisions are successful, however higher temp shifts equilibrium to the left, as it’s an endothermic reaction.

Higher pressure means faster rate as particles closer together so more frequent collisions, and a higher yield as equilibrium shifts to the right, however it’s expensive providing energy and machines to create an even higher pressure, and it’s unsafe