Topic 11 - Equillibrium 2

Question 1

What is Kp?

Answer 1

equilibrium constant in terms of pressure of gases

Question 2

Kp=

Answer 2

p(products)
_________
p(reactants)

-only include gases

Question 3

What is partial pressure?

Answer 3

the force each individual gas exerts on the walls of a container if it were alone

Question 4

partial pressure =

Answer 4

mole fraction x total pressure

Question 5

What is mole fraction?

Answer 5

the fraction of each gas

moles of each gas out of total moles of gas

Question 6

total pressure =

Answer 6

Σpartial pressures

Question 7

What affects the value of the equilibrium constant?

Answer 7

temperature

Question 8

What doesn’t affect the value of the equilibrium constant?

Answer 8

• changes in concentration
• changes in pressure
• presence of catalyst

Question 9

What affect does an increase in temperature have on the value of Kc/Kp in an exothermic reaction?

Answer 9

K decreases

Question 10

Why does Kc/Kp decrease for an exothermic reaction when there is an increase in temperature?

Answer 10

If T increases…
ΔSsurr decreases
so ΔStot decreases
so K decreases

Question 11

What affect does a decrease in temperature have on the value of Kc/Kp in an exothermic reaction?

Answer 11

K increases

Question 12

Why does Kc/Kp increase for an exothermic reaction when there is a decrease in temperature?

Answer 12

If T decreases…
ΔSsurr increases
so ΔStot increases
so K increases

Question 13

What effect does an increase in temperature have on the value of Kc/Kp in an endothermic reaction?

Answer 13

K increases

Question 14

Why does Kc/Kp increase for an endothermic reaction when there is an increase in temperature?

Answer 14

If T increases…
ΔSsurr increases
so ΔStot increases
so K increases

Question 15

What effect does a decrease in temperature have on the value of Kc/Kp in an endothermic reaction?

Answer 15

K decreases

Question 16

Why does Kc/Kp decrease for an endothermic reaction when there is an decrease in temperature?

Answer 16

If T decreases…
ΔSsurr decreases
so ΔStot decreases
so K decreases

Question 17

What effect does an increase in temperature have on the position of equilibrium for an exothermic reaction?

Answer 17

eqm shifts left
because…
If T increases, K decreases
so concentration term no longer equals new, smaller K value
so p(products) must decrease and p(reactants) must increase to decrease the concentration term
to do this equilibrium shifts left until the concentration term re-equals the value of K

Question 18

What effect does an increase in temperature have on the position of equilibrium for an endothermic reaction?

Answer 18

equilibrium shifts right because…
If T increases, K increases
so the concentration term no longer equals the new, larger K value
so p(reactants) must increase and p(products) must decrease to increase the concentration term
to do this equilibrium shifts right until the concentration term re-equals K

Question 19

What effect does an increase in pressure have on the position of equilibrium?

Answer 19

when P increases, all the partial pressures increase but by different amounts (larger powers = increase by greater amount)
this means the concentration term no longer equals Kp
-if there is a larger increase for the denominator (aka reactants), the denominator must decrease and the nominator must increase so that the concentration term increases and eqm shifts left until the concentration term re-equals Kp
-if there is a larger increase for the nominator (aka products), the nominator must decrease and the denominator must increase so that the concentration term decreases and eqm shifts right until the concentration term re-equals Kp