How Do You Calculate Wine Redox Titration Results?

[Spacec0wboy]

Hi guys,

A few days ago we conducted a wine redox back titration in my chemistry class, and my teacher has asked us to calculate to answer all of the questions on a sheet she gave us. Attached is this sheet, outlining the method we followed, the materials used and all the questions she wants us to answer. I know this information will be important too: we titrated 3 samples of 2 different wines and for wine 1 the average titration volume was 30.76mL and for wine 2 it was 24.96mL. Thanks for any help!

 

[Spacec0wboy]

Anyone? I know I'm supposed to provide an attempt of my work but I honestly have no idea on how to even do any of this. I have an extremely good grasp of maths but my knowledge and understanding of chemistry unfortunately does not match this. Even if anyone could get me started it would help.

 

[sjb-2812]

Starting from the beginning then.

What was the concentration of the dichromate solution used?

 

[Spacec0wboy]

ok so far what I've done is (for the dichromate)

n = C x V
therefore n = 0.04M x 0.02L
= 0.0008mol
and for the thiosulfate

n = C x V
n = 0.01M x 0.03076L <------ (that is the average titration volume for wine 1)
n = 0.0003076mol
Does this represent the number of dichromate and thiosulfate ions respectively, or does it just represent the moles of potassium dichromate solution and sodium thiosulfate solution?
Also the next step is confusing, what equation do i use and what sort of stoichiometry do I use?

 

[Spacec0wboy]

Bump

I have progressed a lot with the solutions to the questions posted above in the attached image. Can someone please check my working for me in the attached pdf and notify me if I have done my calculations correctly? Also just for reference, a 5mL wine sample (with double the concentration of a 10mL sample) was used in my case, not a 10mL sample as is specified in the experiment background.

 

[Borek]

I have checked just the first case - and I don't see anything blatantly off. Unfortunately, neither the quality of original image nor quality of pdf are helping in checking the details, which is why I was reluctant to even try. Please, next time do some effort to write these things using computer, so that they are readable.