# Multiple Choice (1 Viewer)

#### iStudent

##### Well-Known Member
but it wants to balance then concentration decreases
Not sure what you mean but when volume decreases concentration of ALL species increases. So you can't say shift left cos Nh3 increased in concentration. See strawberrye's paper similar q.
And it shifts right cos decrease in volume equals increase in pressure. Compare mols of gas.
OK I need to study phys now xD

#### ushnakhalid

##### Member
yooo someone upload a picture of the questions please!

#### enigma_1

##### ~~~~ Miss Cricket ~~~~
@faisalabdul16 pls confirm what the answer to 13 is

#### enigma_1

##### ~~~~ Miss Cricket ~~~~
I'm fakn dying here lol

someone pls upload the MC for us lost souls :/

welp its b then

#### enigma_1

##### ~~~~ Miss Cricket ~~~~
welp its b then
This was yesterday's discussion about a question which emilios posted regarding Lechateliers plus something about volume and pressure.

Came across a Haber question:

"The volume of the reaction vessel was reduced. Explain the changes that occur"

" [formula for Haber process]
When the volume is reduced the concentrations of reactants and products immediately increase, which increases the total pressure. The equilibrium shifts forward to partially counteract this change because there are four moles of reactants and only two moles of products. A forward shift reduces the number of molecules as four react to form two. This reduces the pressure"

Is that actually the correct link between concentration and pressure?

From this, B seems right. http://community.boredofstudies.org...regarding-volumes-pressures-le-chatelier.html

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#### photastic

##### Well-Known Member
2009 Q 23 shows that the same species has the same shape no matter what the change was. Q 13 was stupid because it couldve been A or B but referring to 2009 Q 23, hoping B cos it was initially increasing and I see no reason how it will decrease.

#### Triage

##### Member
2009 Q 23 shows that the same species has the same shape no matter what the change was. Q 13 was stupid because it couldve been A or B but referring to 2009 Q 23, hoping B cos it was initially increasing and I see no reason how it will decrease.
I think I agree with this. It is B for nothing else other than the fact that A wouldn't make sense.

B requires the least suspension of disbelief lol.

#### IR

##### Active Member
My solutions:
1)d
2)a
3)b
4)c
5)c
6)b
7)c
8)b
9)a
10)c
11)a
12)c
13)b
14)d
15)d
16)b
17)a
18)d
19)b
20)d

If you guys can tell me how much would I get, I would appreciate thanks

#### IR

##### Active Member
I think I agree with this. It is B for nothing else other than the fact that A wouldn't make sense.

B requires the least suspension of disbelief lol.
B because when you reduce volume there is a sudden increase in concentration and increase in pressure would occur as a result causing equilibrium to shift to right?

#### enigma_1

##### ~~~~ Miss Cricket ~~~~
someone upload the fknn paper before I go insane lol

#### Triage

##### Member
B because when you reduce volume there is a sudden increase in concentration and increase in pressure would occur as a result causing equilibrium to shift to right?
yes but A and B both satisfy that.

#### chrisdelinet

##### Member
My solutions:
1)d
2)a
3)b
4)c
5)c
6)b
7)c
8)b
9)a
10)c
11)a
12)c
13)b
14)d
15)d
16)b
17)a
18)d
19)b
20)d

If you guys can tell me how much would I get, I would appreciate thanks
they look alriite to me, from a quick glance i say 20/20, unless there was some hidden silly i didn't see yet.

#### Triage

##### Member
I swear they didn't.
a and b both suddenly increase at time T.

A goes slightly above and trends down asymptotically.

B goes slightly below and trends up asymptotically.

#### Thank_You

##### Active Member
15 was easy!

n = V/Mv
Change 'n' to mass/molar mass
Make 'V' the subject.
your mass is constant (1gram) and your molar volume is constant.
Hence you have v = Mv/mm

The smaller the molecular mass the greater the volume. Calculate all molar masses of the answers, and 'D' was the smallest.

I hope thats right :O

#### enigma_1

##### ~~~~ Miss Cricket ~~~~
a and b both suddenly increase at time T.

A goes slightly above and trends down asymptotically.

B goes slightly above and trends up asymptotically.
Oh ok, and according to Le Chatelier, an increase is pressure would shift the equilibrium towards the side with less moles which is the forward direction thus increasing the yield of ammonia and that's why it's B not A, I think.

If someone uploads the paper I will be really grateful

#### jamie_23

##### New Member
13 is b, halving the volume increases the pressure. the equilibrium will then shift to counteract the increase in pressure by decreasing the pressure. 4 moles on the left shift to produce 2 moles on the right therefore decreasing the pressure and increasing the conc of NH3.

#### Triage

##### Member
Oh ok, and according to Le Chatelier, an increase is pressure would shift the equilibrium towards the side with less moles which is the forward direction thus increasing the yield of ammonia and that's why it's B not A, I think.

If someone uploads the paper I will be really grateful
Lol, they both favour an increase in ammonia.

I would upload if I could, don't have a scanner.