[hobomoe]

Acidified potassium dichromate is an oxidant. It will react with titanium metal which is oxidised to form titanium ions.

Show that Ti^3+ and not Ti^2+ if formed in the reaction. Your answer should include chemical equations for any possible reactions and justification for you conclusion based of E values.

E(Cr207^2-/Cr^3+)=+1.33v E(Ti^2+/Ti)=-1.63v E(Ti^3+/Ti^2+)=-2.32v

The attempt at a solution:
E(Cr207^2-/Cr^3+)-E(Ti^2+/Ti)=2.96v
E(Cr207^2-/Cr^3+)-E(Ti^3+/Ti^2+)=3.65v
Dichromate ions react with the titanium metal to form Ti^2+ ions. These ions then react with remaining dichromate ions to form Ti^3+ ions. It will try to form Ti^3+ ions from the Ti^2+ ions in order to get a great E value.

[DevaDevil]

first of all, please use proper BB codes for super and subscripts, this makes your question much easier to read:
[sup ]superscript[/sup ]  and [sub ]subscript[/sub ] (without the spaces)

Now for your question, you have the answer right, but you may want to follow the proper way of writing it down so it is more clear:

-Start with a balanced reaction equation! It is asked of you in the question.

Show that you are using this formula:
ΔE⁰_cell = E⁰_red (cathode) - E⁰_red (anode)

Then note that as long as ΔE⁰_cell is positive, the reaction will occur.

It will try to form Ti^3+ ions from the Ti^2+ ions in order to get a great E value.

Just note that for the oxidation of Ti²⁺ to Ti³⁺, ΔE⁰_cell is still positive and this reaction will therefore occur.



Just make sure to show the reaction equations, so it is clear why you are using the standard potential values that you are using