Organic Chemistry lab for Recrystallization of benzoic acid in distilled water?

Question

1. We use activated charcoal in about the size of pea. What is its role in recrystallization? What happen if we add it too much??

2. Why filter funnel must be warmed before filtering the solution?

Hope u all can help..
Thanks

Answer 1

1. to remove coloured impurities. Too much and your yield will go down.

2. you don't want crystallisation to start in th funnel!

Answer 2

you could desire to establish an ICE chart (I = preliminary, C = replace, E = equilibrium) for a vulnerable acid. HB = cinnamic acid on the precise of the chart, you have HB --> H+ + B- The preliminary volume of HB is a million.6*10^-3 The replace for HB is -x, at a similar time as the replace for H+ and B- is +x The equilibrium volume for HB is a million.6*10^-3 - x The equilibrium volume for H+ is x. Ka = [H+]^2/[HB] So Ka = x^2/(a million.6*10^-3 - x) simply by fact x is that the kind of small type, that's removed from the denominator without inflicting lots disturbance. so which you're left with Ka = x^2/a million.6*10^-3 After plugging in Ka and fixing for x, you get: x = 2.40 3*10^-4 = [H+] -log ([H+]) = pH pH = 3.sixty one