using molar masses:- Theoretical yields:- 63.54 + 2(35.45) g of CuCl2 produces 2(22.98 + 35.45) g of NaCl 134.44 g .................................................... 116.86 g 31.0 g ....................................................31.0 * 116.86 /134.44=26.95g
So percentage yield is 21.2* 100 / 26.95 = 78.7% to nearest tenth