# edexcel chem u4 questionsWatch

Announcements
#1
This question is about the reversible reaction below.
N2O4(g) ⇌ 2NO2(g)
(a) A chemist investigating this reaction started with 5 mol of N2O4 and allowed the system to reach equilibrium. If 2 mol of NO2 forms, the amount of N2O4 at equilibrium is (1)
A 1 mol
B 1.5 mol
C 3 mol
D 4 mol
b) Under different conditions, 25% of the moles of gas present at equilibrium is N2O4.If the total pressure of the system is 3 atm, the numerical value of the equilibrium constant Kp is (1)
A 9.00
B 6.75
C 3.00
D 0.15
in b part of the question how the answer is B? plz help
and this question is from edexcel chem unit 4 june 2015 ial question 6
0
1 month ago
#2
(Original post by mushriqite)
This question is about the reversible reaction below.
N2O4(g) ⇌ 2NO2(g)
(a) A chemist investigating this reaction started with 5 mol of N2O4 and allowed the system to reach equilibrium. If 2 mol of NO2 forms, the amount of N2O4 at equilibrium is (1)
A 1 mol
B 1.5 mol
C 3 mol
D 4 mol
b) Under different conditions, 25% of the moles of gas present at equilibrium is N2O4.If the total pressure of the system is 3 atm, the numerical value of the equilibrium constant Kp is (1)
A 9.00
B 6.75
C 3.00
D 0.15
in b part of the question how the answer is B? plz help
and this question is from edexcel chem unit 4 june 2015 ial question 6
Total pressure = sum of the partial pressures

Partial pressure = mole fraction x total pressure

pp(N2O4) = 0.25 x 3 = 0.75
pp(NO2) = 0.75 x 3 = 2.25

kp = (2.25)2/0.75 = 6.75
0
#3
thankyou so muchhh!!!
(Original post by charco)
Total pressure = sum of the partial pressures

Partial pressure = mole fraction x total pressure

pp(N2O4) = 0.25 x 3 = 0.75
pp(NO2) = 0.75 x 3 = 2.25

kp = (2.25)2/0.75 = 6.75
0
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Imperial College London
Tue, 25 Jun '19
• University of Brighton
Wed, 26 Jun '19
• University of Plymouth
Wed, 26 Jun '19

### Poll

Join the discussion

#### Who do you think will be the next PM?

Boris Johnson (191)
73.46%
Jeremy Hunt (69)
26.54%