3.1.6 Chemical equilibria

Question 1

Give the two things that prove/happen when a reaction is at equilibrium

Answer 1

Forward and reverse reactions are occurring at the same rate
The concentration of reactants and products remain equal

Question 2

If at equilibrium are the concentration of reactants and products the same

Answer 2

No
They can be but it’s not a requirement
The concentrations must be constant but not necessarily the same

Question 3

What is a closed system

Answer 3

No substances (products or reactants) are added to the system or are lost from it
Nothing leaves or enters the system

Question 4

Why is it called DYNAMIC equilibrium

Answer 4

Both forward and reverse reactions are occurring

Question 5

Which side does equilibrium have to be approached from

Answer 5

Either
Products or reactants

Question 6

If enthalpy change sign is positive then forward reaction is

Answer 6

Endothermic

Question 7

If the enthalpy change sign is negative then the forward reaction is

Answer 7

Exothermic

Question 8

Increase temperature in equilibrium favours

Answer 8

Endothermic direction

Question 9

Decrease temperature at equilibrium favours

Answer 9

Exothermic direction

Question 10

What effect do catalysts have on equilibrium

Answer 10

No effect on position
But decrease time taken to reach equilibrium because it increases rate of forward and reverse reaction by the same amount

Question 11

What effect does increasing pressure have on equilibrium

Answer 11

Shifts to side with less molecules

Question 12

What effect does decreasing pressure have on equilibrium

Answer 12

Shifts to side with more molecules

Question 13

Pressure only effects equilibrium when….

Answer 13

All substances are gases

Question 14

What happens if we increase concentration of one of the substances at equilibrium

Answer 14

It will shift to the opposite side
( to explain why kinda confusing look in book)

Question 15

State le chateliers principle

Answer 15

If a reaction is at equilibrium is subjected to change in pressure, temperature or concentration the position of equilibrium will move to counteract the change

Question 16

Equilibrium can only happen when…..

Answer 16

Only in homogeneous reactions
All in the same state

Question 17

Expression for Kc

Answer 17

Products / reactants

Question 18

What is acronym for finding Kc concentrations

Answer 18

I - initial MOLES
C - change in MOLES
E- MOLES at equilibrium

Question 19

All substance in equilibrium has the ….. volume

Answer 19

Same

Question 20

Effect of catalysts on Kc

Answer 20

None

Question 21

Effect of concentration on Kc

Answer 21

None

Question 22

Effect of temperature on Kc

Answer 22

Yes
Look in book for how and explanation

Question 23

What do the measurements for Kc have to be in

Answer 23

Concentration

Question 24

Why can percentage uncertainty be okay for some experiments

Answer 24

Temperature CHANGE etc is bigger than the uncertainty

Question 25

What effect does the catalyst have on the equilibrium constant

Answer 25

None

Question 26

What is the one thing that effects equilibrium constant

Answer 26

Temperature

Question 27

What effect does catalysts have on the rate of the reverse reaction

Answer 27

Increases it

Question 28

When doing ICE for equilibrium moles does big numbers matter

Answer 28

YES

Question 29

If you remove the product as it forms does this increase the yield of the product

Answer 29

Yes