C19 - Equilibrium

Question 1

How do you calculate the units for Kc

Answer 1

Question 2

What are the two types of equilibria

Answer 2

Homogeneous
Heterogeneous

Question 3

What is homogeneous equilibrium

Answer 3

Equilibrium species that all have the same state

Question 4

What is heterogenous equilibrium

Answer 4

Equilibrium species that have different states

Question 5

When calculating heterogeneous Kc what is omitted

Answer 5

Liquid and solid substances

Question 6

Answer 6

Question 7

How can Kc be determined from experimental results

Answer 7

Question 8

How do you calculate Kc from this experiment

Answer 8

Question 9

When calculating homogeneous Kc what is omitted

Answer 9

Nothing

Question 10

What is Kp

Answer 10

Equilibrium constant in terms of partial pressures

Question 11

When is Kp used

Answer 11

For equilibria involving gases

Question 12

What is a mole fraction of a gas

Answer 12

Same as its proportion by volume go the total volume of gases in a gas mixture

Question 13

Formula for mole fraction

Answer 13

Mole fraction x(A) = number of moles of A / total numbers of moles in a gas mixture

Question 14

How do you calculate mole fractions

Answer 14

Question 15

What is partial pressure?

Answer 15

p
Contribution that a gas makes towards the total pressure

Question 16

Partial pressure calculations

Answer 16

partial pressure p(A) = mole fraction of A x total pressure (P)
p(A) = x(p) x P

Question 17

How do you calculate partial pressures

Answer 17

Question 18

How do you write out Kp?

Answer 18

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

Question 19

What are units for Kp

Answer 19

kPa, Pa, atm

Question 20

How do you calculate Kp for homogenous equilibrium

Answer 20

Question 21

How do you calculate Kp for heterogeneous equilibrium

Answer 21

Question 22

What 3 rules does le Chatilier’s principle outline?

Answer 22

1) If conc of species inc, eq p shifts in direction that reduces conc
2) If pressure inc, eq p shifts to side w/ fewer gaseous moles
3) If temp inc, eq p shifts to endothermic direction

Question 23

Does equilibrium constant change?

Answer 23

K gives position of eq
K does not change at same temp

Question 24

What factors cause K to change

Answer 24

Only temp

Question 25

What effect does changing temp have on K in forward exothermic reactions

Answer 25

-K dec with inc temp -Inc temp dec eq yield of products

Question 26

What effect does changing temp have on K in forward endothermic reactions

Answer 26

-K inc with inc temp -Inc temp inc eq yield of products

Question 27

How can you explain the equilibrium shift due to inc temp in exothermic reactions

Answer 27

Kp dec System not in equilibrium Kp equation is greater than Kp Partial pressure of products dec Partial pressures of reactants inc Eq position shifts to reactants

Question 28

How can you explain the equilibrium shift due to inc temp in endothermic reactions

Answer 28

Kp inc System not in equilibrium Kp equation is less than Kp Partial pressure of products inc Partial pressures of reactants dec Eq position shifts to products

Question 29

How does Kc change with temp

Answer 29

Same way as Kp

Question 30

How do changes in conc and pressure affect equilibrium?

Answer 30

K is unaffected -equilibrium shift results from fact K does not change

Question 31

How do catalysts affect K

Answer 31

No effect -speeds up rate of both forward and backward reaction but not position of eq -eq reached quicker