1. The problem statement, all variables and given/known data Well we have this lab on equilibrium using titration. I found the lab here http://wikieducator.org/Chemistry/Equilibrium_Titration" [Broken] So I'm kinda stuck on number 3c, where it asks what is the starting concentration of Fe3+. I don't know if I did number 3b right either... 2. Relevant equations Everything is on that webpage. 3. The attempt at a solution 1a) 0.05 M b)0.05 M 2)0.0013 mol ( volume of KSCN used was 13mL) 3a) nAg=nKSCN = 0.0013 mol For 3b) what I did was take the starting moles and subtracted the end number of moles. So I calculated that there were 0.003mol in the starting solution of 0.05M Ag+ and then 0.00013mol of Ag+ at equilbrium. I then got 0.0017mol as the moles at equilibrium. It is the concentration that I'm not really sure to what I'm doing. So what I did was take 0.05M (concentration of diluted Ag) and then subtracted the concentration of Ag at equilibrium. For the equilibrium concentration, I put 0.0013mol / (0.05L + 0.05L + 0.013L) but I dont think this is right.. What should I do here? For 3c, would the starting amount of Fe3+ be zero? Any help will be appreciated. Thanks.