• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

Can someone help me with these chemistry questions (1 Viewer)

sunshine_c22

Member
Joined
Nov 23, 2021
Messages
40
Gender
Female
HSC
N/A
Hi,
I am stuck with these questions and i'm not getting the answer can someone please provide me with the answer + explanation
1684318709381.png
1684318770152.png
 

carrotsss

New Member
Joined
May 7, 2022
Messages
4,472
Gender
Male
HSC
2023
5. It will not shift as there are equal moles of gas on each side. This means that favouring either side would be pointless, as neither shift would decrease the pressure.

6. Try to do this question yourself. Remember that Keq=[products]/[reactants], and if there’s a two/three in front of something then you have to square/cube its concentration for Keq

7. Same as question 6, give it a go yourself, it should be pretty simple. The equation for Qc is identical to the equation for Keq, and you’ve been given all of the concentrations so you just have to sub into equations

8. For this question, set up your equation for Kc e.g. Kc=[CH3OH][CO]/[CH3COOH], then sub in your values for the concentrations you’ve been given and for Kc. If you rearrange the equation, you’ll be able to find [CH3COOH]

9. Draw a RICE table, where cis-but-2-ene has an initial concentration of 1 and trans-but-2-ene has an initial concentration of 0. Then, there’s a change in concentration of s for both into equilibrium (1:1 ratio). If you sub these equations (1-s and s) into Kc you should be able to solve for s, which is your answer
 

sunshine_c22

Member
Joined
Nov 23, 2021
Messages
40
Gender
Female
HSC
N/A
5. It will not shift as there are equal moles of gas on each side. This means that favouring either side would be pointless, as neither shift would decrease the pressure.

6. Try to do this question yourself. Remember that Keq=[products]/[reactants], and if there’s a two/three in front of something then you have to square/cube its concentration for Keq

7. Same as question 6, give it a go yourself, it should be pretty simple. The equation for Qc is identical to the equation for Keq, and you’ve been given all of the concentrations so you just have to sub into equations

8. For this question, set up your equation for Kc e.g. Kc=[CH3OH][CO]/[CH3COOH], then sub in your values for the concentrations you’ve been given and for Kc. If you rearrange the equation, you’ll be able to find [CH3COOH]

9. Draw a RICE table, where cis-but-2-ene has an initial concentration of 1 and trans-but-2-ene has an initial concentration of 0. Then, there’s a change in concentration of s for both into equilibrium (1:1 ratio). If you sub these equations (1-s and s) into Kc you should be able to solve for s, which is your answer
I've tried! But I'm literally not getting the answers :(
 

Eagle Mum

Well-Known Member
Joined
Nov 9, 2020
Messages
561
Gender
Female
HSC
N/A
I've tried! But I'm literally not getting the answers
Do they provide the answers to questions 6 & 7? @carrotsss has provided you with the correct approach, so if you provide their answers, we can determine if the textbook might be wrong (happens not uncommonly) and possibly reverse engineer from the answer.
 

sunshine_c22

Member
Joined
Nov 23, 2021
Messages
40
Gender
Female
HSC
N/A
Do they provide the answers to questions 6 & 7? @carrotsss has provided you with the correct approach, so if you provide their answers, we can determine if the textbook might be wrong (happens not uncommonly) and possibly reverse engineer from the answer.
It's a quiz, and it doesn't tell me the answers, it only says its wrong
 

Eagle Mum

Well-Known Member
Joined
Nov 9, 2020
Messages
561
Gender
Female
HSC
N/A
I’m not sure what they are trying to test with question 5.
carrotsss is correct about pressure per se not affecting the equilibrium when there are equal moles of gases on each side, but then the question mentions that the (forward) reaction is exothermic, so I don’t know if they are trying to test knowledge that pressure is proportional to temperature and therefore by heating the system, you’d favour the endothermic direction (ie. to the left).
 

sunshine_c22

Member
Joined
Nov 23, 2021
Messages
40
Gender
Female
HSC
N/A
5. It will not shift as there are equal moles of gas on each side. This means that favouring either side would be pointless, as neither shift would decrease the pressure.

6. Try to do this question yourself. Remember that Keq=[products]/[reactants], and if there’s a two/three in front of something then you have to square/cube its concentration for Keq

7. Same as question 6, give it a go yourself, it should be pretty simple. The equation for Qc is identical to the equation for Keq, and you’ve been given all of the concentrations so you just have to sub into equations

8. For this question, set up your equation for Kc e.g. Kc=[CH3OH][CO]/[CH3COOH], then sub in your values for the concentrations you’ve been given and for Kc. If you rearrange the equation, you’ll be able to find [CH3COOH]

9. Draw a RICE table, where cis-but-2-ene has an initial concentration of 1 and trans-but-2-ene has an initial concentration of 0. Then, there’s a change in concentration of s for both into equilibrium (1:1 ratio). If you sub these equations (1-s and s) into Kc you should be able to solve for s, which is your answer
Is the answer for question 6 = 0.39
Question 7 = 0.91
Question 8= 0.94
I still can't figure out question 9
 

Eagle Mum

Well-Known Member
Joined
Nov 9, 2020
Messages
561
Gender
Female
HSC
N/A
Is the answer for question 6 = 0.39
Question 7 = 0.91
Question 8= 0.94
I still can't figure out question 9
We agree on the answers to Q6 and Q8.

I get 1.52 as the answer to Q7.
 
Last edited:

Eagle Mum

Well-Known Member
Joined
Nov 9, 2020
Messages
561
Gender
Female
HSC
N/A
For Q9,

K = [product] / [reactant]
= [trans] / [cis]
0.17 = [trans] / 1
[trans] = 0.17 M
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top