[miked87]

Hello... I was wondering if anyone could help...

 I am currently on a SKE and all the experiments and questions I have got but this one for some reason is not going well...

 I have attached the Salters A level iodine clock experiment...

 The questions at the bottom I am stuck on....

 Question 1-3 I can do

 Question 4 and 5 I can't.... anyone know how I work them out?

 The answers are:

 4. 8 x 10-5 mol
 5a 2 x 10-5 mol S2O3^2-
 5b 1 x 10-5 mol I2
 5c 12.5%

 If anyone could help that be greatly appreciated?

 Thanks

[Burner]

For 4), start by writing a balanced chemical equation between I^- and S₂O₈^2- first. Then use the mole ratio and number of moles of the limiting reagent you found in 3) to calculate the answer.

5a is easy. Just use the volume and concentration of S₂O₃^2- to calculate the answer.

5b you have to write a balanced equation between I₂ and S₂O₃^2- first.

5c not sure(I haven't learnt 'extent of reaction')

By the way, re-read the Forum Rules: http://www.chemicalforums.com/index.php?topic=65859.0. You should show your attempts/thoughts at the problem when trying to receive help here.