Suppose 1.74 g of cobalt (II) sulfide was isolated and recovered, what is the weight percent of NaCl in the original sample (3.18 g)? A sample which is having 3.18 g of a mixture of CoCl2 and NaCl was dissolved in the water, and the solution treated with the hydrogen sulfide (H2S) to precipitate the cobalt as cobalt (II) sulfide.