How many grams of chloride ions are in 8.3 g of copper (II) chloride

2.4 grams.

Explanation

Refer to a modern periodic table for relative atomic mass:

Cu - 63.546; Cl - 35.45.

Formula of copper (II) chloride: CuCl₂.

Formula mass of copper (II) chloride:

63.546 + 2 * 35.45 = 240.796 g / mol.

How many moles of formula units in 8.3 grams of CuCl₂?

8.3 / 240.796 = 0.0345 moles.

Note the subscript "2" in the formula CuCl₂. There are two moles of chloride ions in each formula unit of CuCl₂.

There are 2 * 0.0345 = 0.0689 moles of Cl ions in 0.0345 moles formula units of CuCl₂.

The mass of one mole of chloride ion is 35.45 grams.

The mass of 0.0689 moles of chloride ions will be 35.45 * 0.0689 = 2.4 grams.

Round the final value to two sig. fig. since the mass in the question is also 2 sig. fig.

8.3g of CuCl2 = 0.123 mol of chloride ions = 4.4 g of chloride ions