equilibrium constant Kp

Question 1

what is Kp used for

Answer 1

to find equilibrium constant based on partial
pressures at a particular temp

Question 2

what is the Kp expression

Answer 2

partial pressure of products/ partial pressure of reactants

Question 3

what values do you use for the equation

Answer 3

ones given in question - no need to convert - can either be tonnes or grams

Question 4

what are the untis of Kp

Answer 4

• either Pa or kPa - just use what is in the question

to convert from Kpa to Pa - x1000

Question 5

what must all reactants and products be in

Answer 5

gas phase - as it is for an homogenous system

Question 6

how to find partial pressure of each molecule

Answer 6

ICE
then find total mol at eq
divide mol/total
then x by total pressure

Question 7

what term is used to descriube the partial pressure dependent on the no. of moles present in a mixture

Answer 7

mole fraction

Question 8

example

Answer 8

calculate partial pressure of these gases at eq
2 mol of A , 2 mol B and 3 mol C total pressure is 2 kPa

total mol = 2+2+3 = 7
pA = 2/7 x 2 = 0.57 kPa
pB = 2/7 x 2 = 0.57 kPa
pC = 3/7 x 2 = 0.86 kPa

then sub into Kp and work out eq

Question 9

does the value of Kp change when add a catalyst

Answer 9

no

Question 10

does the value of Kp change when change conc/ pressure/ vol

Answer 10

no

Question 11

does the value of Kp change when change temp

Answer 11

yes

increase - Kp decreases if forward is exo
deacrease - Kp increase if forward is exo

Question 12

what is partial pressure proportional to

Answer 12

no. of moles

Question 13

what to remember to include in Kp expression

Answer 13

p in front of the moelcules