Chemical equilibrium

Question 1

What is equilibrium?

Answer 1

• The state in which there are no observable changes over time

Question 2

What are the requirements for equilibrium?

Answer 2

• Closed system
• Constant temperature, pressure
• Reversible process/reaction
• Rates of opposing changes are equal

Question 3

Equilibrium systems are D______, R______, can approach from either direction. Both reactants and products present at all times

Answer 3

• Dynamic

* Reversible

Question 4

At the point where the rate of the forward reaction equals the rate of the backwards reaction , what has the reaction reached?

Answer 4

• Dynamic equilibrium

Question 5

The rate of the forward reaction equals to the rate of the R_____ reaction

Answer 5

• Reverse

- the forward and reverse reactions continue at equal rates in both directions

Question 6

What is meant by the reaction quotient, Q?

Answer 6

• Relates the amounts of products and reactants to each other at any point in a reaction

Question 7

What is meant by the equilibrium constant, K?

Answer 7

• Value of the reaction quotient at equilibrium

does not depend on initial amounts of reactants and products

Question 8

REVIEW HOW TO WRITE EQUILIBRIUM EXPRESSIONS

Answer 8

REVIEW HOW TO WRITE EQUILIBRIUM EXPRESSIONS

Question 9

Describe the similarity between reactants and products at homogenous equilibrium

Answer 9

• Reactants and products are in the same physical state

Question 10

Describe the difference between reactants and products at heterogenous equilibrium

Answer 10

• Reactants and products are in different physical states

Question 11

REVIEW CALCULATING K

Answer 11

REVIEW CALCULATING K PART ||

Question 12

Initial state:
a)All reactants b)Mostly reactants
c)Equilibrium d)Mostly products
e)All products
State the change for each state

Answer 12

a) shift right
b) shift right
c) none
d) shift left
e) shift left

Question 13

Small K favours…..

Large K favours…..

Answer 13

Small K: favours reactants

Large K: favours products

Question 14

True or false

- Little reaction occurs with a large K

Answer 14

FALSE

• With a large K the reaction is nearly complete where as with a small K little reaction occurs

Question 15

State Le chatelier’s main principle

Answer 15

“When a change is applied to a system in dynamic equilibrium, the system reacts in such a way as to oppose the effect of the change”

Question 16

Describe how a reactant/product change affects equilibrium constant

Answer 16

• Equilibrium constant is not affected by a change in reactant/product concentration at constant temperature

Question 17

Describe the equilibrium position of osmosis

Answer 17

• Equal concentrations either side of the membrane

Question 18

Changing pressure only affects reactions with different number of ___ molecules each side

Answer 18

• Gas

- the more particles you have in a given volume, the greater the pressure they exert

Question 19

Adding a C_____ does not affect the position of equilibrium

Answer 19

• Catalyst

- Note: it does increase the rate of reaching equilibrium

Question 20

T_________ is the only thing that can change the value of the equilibrium constant

Answer 20

• Temperature

- Equilibrium moves and created a mew equilibrium constant