amo17
Badges: 2
Rep:
?
#1
Report Thread starter 12 years ago
#1
A disproportionation reaction occurs when a species M+ spontaneously undergoes simultaneous
oxidation and reduction.
2M+(aq) → M2+(aq) + M(s)
The table below contains E data for copper and mercury species.
Using these data, which one of the following can be predicted?
A Both Cu(I) and Hg(I) undergo disproportionation.
B Only Cu(I) undergoes disproportionation.
C Only Hg(I) undergoes disproportionation.
D Neither Cu(I) nor Hg(I) undergoes disproportionation.


the answer is B, but does anyone understand how to get it?

Any help appreciated
Thanks
0
reply
Wenzel
Badges: 0
Rep:
?
#2
Report 12 years ago
#2
(Original post by amo17)

The table below contains E data for copper and mercury species.
Using these data, which one of the following can be predicted?
I think we need this table first.
0
reply
amo17
Badges: 2
Rep:
?
#3
Report Thread starter 12 years ago
#3
sorry, didn't notice that this didn't copy too.

Cu2+(aq) + e– → Cu+(aq) + 0.15
Cu+(aq) + e– → Cu(s) + 0.52
Hg2+(aq) + e– → Hg+(aq) + 0.91
Hg+(aq) + e– → Hg(l) + 0.80

Thanks
0
reply
Wenzel
Badges: 0
Rep:
?
#4
Report 12 years ago
#4
Well the first equation (2M+(aq) → M2+(aq) + M(s)) tells you that during disproportionation, an aqueous 2+ ion and and a solid is formed. From the E values you can see that C+ forms a solid, where as Hg+ forms a liquid; so the only possible answer can be B.

Not sure if there's any other way of doing this question, but that's how I'd work it out.
0
reply
charco
Badges: 17
Rep:
?
#5
Report 12 years ago
#5
To do the copper disproportionation the hypothetical equation would involve reacting the reverse of equation 1 with equation2 (from the data list)

The Cu+ in equation 1 is the species getting oxidised and the Cu+ in equation 2 is the species getting reduced.

E = E(red) - E(ox) = +0.52 - +0.15 = +0.37
This is a positive value and larger than 0.3 suggesting that the system is both feasible and spontaneous and will go all the way.

Repeat the same process for the mercury...
1
reply
Carlo08
Badges: 0
Rep:
?
#6
Report 12 years ago
#6
Its:

Cu+ + Cu+ -------> Cu + Cu^2+

The copper (i) has oxidised the other and it has been reduced itself.
0
reply
Da14a
Badges: 16
Rep:
?
#7
Report 3 months ago
#7
(Original post by charco)
To do the copper disproportionation the hypothetical equation would involve reacting the reverse of equation 1 with equation2 (from the data list)

The Cu+ in equation 1 is the species getting oxidised and the Cu+ in equation 2 is the species getting reduced.

E = E(red) - E(ox) = +0.52 - +0.15 = +0.37
This is a positive value and larger than 0.3 suggesting that the system is both feasible and spontaneous and will go all the way.

Repeat the same process for the mercury...
Thank you for this from 12 years in the future. :banana:
1
reply
charco
Badges: 17
Rep:
?
#8
Report 3 months ago
#8
(Original post by Da14a)
Thank you for this from 12 years in the future. :banana:
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

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

Personalise

What factors affect your mental health the most right now?

Anxiousness about lockdown easing (187)
5.02%
Uncertainty around my education (545)
14.62%
Uncertainty around my future career prospects (417)
11.19%
Lack of purpose or motivation (513)
13.76%
Lack of support system (eg. teachers, counsellors, delays in care) (184)
4.94%
Impact of lockdown on physical health (222)
5.95%
Loneliness (313)
8.4%
Financial worries (138)
3.7%
Concern about myself or my loves ones getting/having been ill (145)
3.89%
Exposure to negative news/social media (168)
4.51%
Lack of real life entertainment (212)
5.69%
Lack of confidence in making big life decisions (333)
8.93%
Worry about missed opportunities during the pandemic (351)
9.42%

Watched Threads

View All