Mina_
Badges: 8
Rep:
?
#1
Report Thread starter 4 years ago
#1
The redox potential for a transition metal ion changing from a higher to a lower oxidation state is influenced by pH and by the ligand.

and

know that carboxylic acids are weak acids but will liberate CO2 from carbonates
0
reply
Bence9912
Badges: 9
Rep:
?
#2
Report 4 years ago
#2
Cant comment on transition metals yet as we have not done it.

But reacting carboxylic acid w/ carbonates e.g(CaCO3) will give of CO2 (you can test this by bubbling effervescence through limewater turning it cloudy).

Carboxylic acids also dissociate partially in water to carboxylate ions to give weak acids (this is a reversible reaction)
0
reply
Kvothe the Arcane
Badges: 20
Rep:
?
#3
Report 4 years ago
#3
(Original post by Mina_)
The redox potential for a transition metal ion changing from a higher to a lower oxidation state is influenced by pH and by the ligand.
Transition metals, like chromium, can exist in an equilibrium with H+. See below:
\mathrm{2CrO_4^{2-}_{(aq)} + 2H^+_{(aq)} ⇌ Cr_2O_7^{2-}_{(aq)} + H_2O_{(l)}}
The pH will shft the equilibrium of ths system to the left or right depending on whether it's alkali or acidic and there is a difference in redox potential between the chromate (VI) and dichromate (VI) ions.

know that carboxylic acids are weak acids but will liberate CO2 from carbonates
\mathrm{2CH3(CH2)_nCOOH+YCO3 \rightarrow (CH3(CH2)_nCOO)_2Y+CO_2+H_2O}
2
reply
MexicanKeith
Badges: 12
Rep:
?
#4
Report 4 years ago
#4
(Original post by Mina_)
The redox potential for a transition metal ion changing from a higher to a lower oxidation state is influenced by pH and by the ligand.

and

know that carboxylic acids are weak acids but will liberate CO2 from carbonates
In terms of ligands influencing the transition metal redox potentials you don't have to know very much. Just the idea that different ligands form bonds of different strengths to transition metals.

generally this means some ligands stabilise higher oxidation states more than lower ones and other ligands visa versa, so different ligands change how easy it is to change the metal oxidation state, hence the redox potential is changed by the ligand.

The actual reasons for the specific behavious of certain ligands can only really be justified by molecular orbital theory which is way beyond anything you need to worry about at A level
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 support do you need with your UCAS application?

I need help researching unis (25)
13.66%
I need help researching courses (12)
6.56%
I need help with filling out the application form (9)
4.92%
I need help with my personal statement (76)
41.53%
I need help with understanding how to make my application stand out (44)
24.04%
I need help with something else (let us know in the thread!) (3)
1.64%
I'm feeling confident about my application and don't need any help at the moment (14)
7.65%

Watched Threads

View All