[xshadow]

Hi!!
I have a doubt about the titration curve of a redox reaction

I have as titrand  a 50ml solution of Cr³⁺ 0.02M and as titrant a Sn2+ 0.1M solution in HCl 1M

I know that E°(Cr³⁺/²⁺)=-0.40V while E°(Sn⁴⁺/²⁺) = 0.14V


I've calculated the potential E gpr phi=0.001 using thos formula
Phi<1

E=E°(Cr³⁺/²⁺) +RT/nF ln( 1-phi / phi)

I get E= -0.577V for phi=0.001

But the tritatipn curves I usually see have always positive vute for "E"

Can a negative value be possibile? Can the tritation occour anyway?
Thanksss!

[Hunter2]

In this reaction chromium get reduced and tin oxidised. The opposit is not possible.

E = Eox- E red

Use for E the Nernst  equation and the concentration of both ions.

The value should be positive.

[xshadow]

In this reaction chromium get reduced and tin oxidised. The opposit is not possible.

E = Eox- E red

Use for E the Nernst  equation and the concentration of both ions.

The value should be positive.

You mean I have to calculatw E(Cr³⁺/²⁺ us8ng the nersy equation??

And do the same thing for Tin?

Because using the standard potential I have: -0.40 + 0.14 = negqtive value

Using the nernst equation will be ok?
Thanks v)

[Hunter2]

No it's opposit 0,14V -(-0,4V) = 0,54 V for E0 if both have same concentration.

But you have to develop E = E0  + RT/zF ln cox/cred for both elements

https://www.google.com/url?q=https://m.youtube.com/watch%3Fv%3DjousNNceCXs&sa=U&ved=2ahUKEwjHxoHy4MP4AhWASfEDHazLD-0QtwJ6BAgEEAE&usg=AOvVaw1lNWWG0OJeQ1QH3ngziGNm

[xshadow]

No it's opposit 0,14V -(-0,4V) = 0,54 V for E0 if both have same concentration.

But you have to develop E = E0  + RT/zF ln cox/cred for both elements

https://www.google.com/url?q=https://m.youtube.com/watch%3Fv%3DjousNNceCXs&sa=U&ved=2ahUKEwjHxoHy4MP4AhWASfEDHazLD-0QtwJ6BAgEEAE&usg=AOvVaw1lNWWG0OJeQ1QH3ngziGNm

But if Cr3+ is reduced it means it's the catodhe  so the correct formula should be:

E cathode - E anode= E(Cr3+/2+) - E(Sn4+/2+)= -0.40 -(0.14)

The opposite!!...

[Meter]

In this reaction chromium get reduced and tin oxidised. The opposit is not possible.

E = Eox- E red

Use for E the Nernst  equation and the concentration of both ions.

The value should be positive.

Am I missing something? otherwise your equation should be E = E(red) - E(ox)

[Hunter2]

You are right it is the opposit E = Ered- Eox

What means this reaction cannot take place. The opposit would be the case Chromium II will be oxidised by tin IV to chromium III and tin II.