PbCl2(s) = Pb+2(aq) + 2Cl -(aq).

For every mole of Pb+2 ions that are formed, how many moles of Cl- ions are formed?

I know the Atomic weight is 35.45 but how do you change grams to moles?

Though the reaction you mentioned is quite strange, for PbCl2 is a solid that is insoluble in water... cold water I mean.

Ok, have a look at your equation. The number put in front of each formula indicates the number of moles of that particular substance.
If there is nothing, meaning 1, there is one mole. If there is a 2, there are 2 moles! And so on...

Ok, for the conversion from grams to moles, you have to know that one mole of a substance has a mass equal to it's relative atomic, molecular or formula mass and add the units grams (g) after that.

Take hydrogen gas, H2 (relative atomic mass of H=1)
Relative molecular mass of H2= 2x1 = 2
One mole of H2 will therefore have a mass of 2g

Understood? :)