Cu++ forms a blue-green complex with tetraphenylporphin in a 1:1 ratio. Say you have 100 mL of a 2.0 x 10^-4 solution of the Tetraphenylporphin. Exactly what weight of CuCl2 must be added to the solution to insure complete complexation without any excess cupric chloride remaining?

Answer 1

How many mols of the tetraphenylporphin do you have? That's mols = M x L = ?

Since the ratio is 1:1 you have that same number of mols Cu^2+ and the same number of mols of CuCl2.

Then mass CuCl2 = mols CuCl2 x molar mass CuCl2.