You now know that [Pb+2] = 0.17 M. Calculate [Cl-].

0.34 M

Explanation:

I assume that the compound is PbCl2.

One mole of PbCl2 contains one mol of Pb+2 and 2 moles of Cl-

Molarity (M)= moles (n) /Volume (V)

Moles Pb2+ = M x V = 0.17 V

Moles Cl- = moles Pb2+ x (2 moles Cl-/1 mole Pb2+) = 0.17 V x 2 = 0.34 V

M Cl- = moles Cl-/V = 0.34V/V = 0.34 M

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.