XtremePapers

Will check on the titration question and let you know the exact answer. Gotta know the exact analyte and titre. Will have a look in a while.

P2O5 is the formula

Alright, so its a titration between FeSO4 and KMnO4.
I think you thought that the colour change is from pale green to rusty brown. But instead of rusty brown its pink. The reason is this.
Practically, if you do this titration, you would get punk at the point. This is because you add phosphoric acid into the analyte which makes the rusty brown Fe3+ being formed to appear colourless.

This is because the rusty brown is like an interference in finding the colour change. So at the end point, EXCESS KMnO4 is added so pink is seen at the end point. Although, nothing is mentioned about phosphoric acid in the question, it is added when doing this titration practically. Therefore, pink is correct

I think it is pink because.

Iron (ii) sulphate is GREEN in color.
Iron (iii) Sulphate is YELLOW.

When KMnO4 is added from the burette, the Iron ii ions are oxidized to Fe +3 ions. That causes the color to change to yellow. And when the final drop of purple KMnO4 falls, the purple color mixes with the yellow color to give a uniform pink color.

A very similar Q came in 2009 MJ P4.
Here,it was scrap iron and KMnO4.
So there are no compounds but still the end point colour is pink due to H3PO4 being added to neutralize the rusty brown colour

Therefore, you cant use the compound colour reasoning in this sort of question.
I'm not saying your wrong but its just that it cannot be applied to any question

What I meant previously was that you can't use that reasoning in "any" sort of question

But there was no mention about adding Phosphoric acid in this question.
How would candidates know the right answer then?

Although, Phosphoric isn't mentioned, it is added when the titration is done practically. It is recommended to have done such practicals and I guess Cambridge expects us to know the practical aspects of chemistry and apply that knowledge in answering the question in th atp

sorry to interrupt, but in this case, we assume that the oxidising agent has been added in excess, that causes it to go colourless when titration ends, but an excess will cause it to go pink

But what about the color of Iron (iii) sulfate?

Remember that the colour of the indicator is more dominant.

What is the color of Iron iii sulfate solution? Is it red-brown or yellow?

red-brown

But isnt red brown a more dominant colour than pink?