Chemical Eauilibria

Question 1

What is dynamic equilibrium?

Answer 1

Where in a reversible reaction, the rate of the forward reaction = rate of reverse reaction
The concentration of products and reactants remains constant

Question 2

Where does the position of equilibria lie?

Answer 2

To the side that has the highest concentration of

Question 3

What is Le chateliers principle?

Answer 3

If a sustem in equilibrium is opposed to change, the position of equilibrium will shift in the direction that will oppose the change

Question 4

How does a change in concentration effect the position of equilibrium?

Answer 4

If the conc of reactants increases the position will shift to the right, to increase the conc on lroducts and oppose the change

Question 5

What happens to the position of equilibrium if the total pressure increases?

Answer 5

Position shifts to the side of the reaction that has the least moles lf gas, to oppose the change. This will produce fewer moles lf gas to decrease the pressure

Question 6

How does change in temperature effect the positipn of equilibrium?

Answer 6

If the temp increases, it shifts to the direction of the endothermic reaction, to oppose the change in temperature in the endothermic reaction. This decreases the temperature

Question 7

How does a catalyst effect the position of equilibrium?

Answer 7

It does not shift the position, the activation energy is lowered by the same amount in both the exothermic and endothermic reaction. The rate increases by the same for each

Question 8

What is the haber process?

Answer 8

The process lf making ammonia through the reversible reaction between
N2 + 2H2 <-> 2NH3

Question 9

Is the forward reaction of the harber process endo or exothermic?

Answer 9

Exothermic

Question 10

What temperature is used in the haber process? Why is described as a comprimise?

Answer 10

Between 400-500*C
So there is a balance between a high yield and fast rate of reaction

Question 11

What conditions are used in the haber process?

Answer 11

200 atm
400-500*C
Iron catalyst
Recycling (reduce costs of products)

Question 12

What is Kc?

Answer 12

The equilibrium constant of a reversible reaction, in terms of the concentrations of the reactants and products

Question 13

What is the ewuation for Kc?

Answer 13

Comcentration of products / concentration of reactants
Where the products and reactants are at equilibrium

Question 14

What is the significance pf Kc and what does it tell us about the composition of a mixture when at equilibrium?

Answer 14

If Kc is less than 1, there is a higher conc of reactants than products
If Kc is more than 1, there is a higher conc of products than reactants

Question 15

How do you calculate the units for Kc?

Answer 15

Stoichipmetric moles of products/ reactants.

Question 16

How does tempersture effect the value of Kc?

Answer 16

If temperature change causes the position of equilibrium to shift to the right, Kc will increase, if to the left Kc will decrease

Question 17

How does pressureaffect the value of Kc?

Answer 17

It doesn’t not

Question 18

When calculating Kc, what happens when there are the same number of moles on each side of the equilibrium?

Answer 18

The volumes cancel, so the number of moles can be used instead of concentration
There are no units

Question 19

How do you calculate the value of Kc from initial amounts of products/ reactants?

Answer 19

RICE:
Ratios
Initial moles used
Change in moles
Final molesat equilibrium

Use final moles and volumes to calculate concentrations at equilibrium, use that to find Kc