How many moles of chloride ions, Cl- , are there in 0.50g of copper(II) chloride, CuCl2?

There are 0.0074 mol of Cl⁻ ions in 0.50 g of CuCl₂.

The formula tells you that there are 2 mol of Cl⁻ in 1 mol of CuCl₂. So we must find the moles of CuCl₂.

We must convert grams of CuCl₂ → moles of CuCl₂ → moles of Cl⁻

0.50 g CuCl₂ × ##(1"mol CuCl₂")/(134.4"g CuCl₂") × (2"mol Cl⁻")/(1"mol CuCl₂")## = 0.0074 mol Cl⁻