E.29 b and c

[JustinHorriat_4f]

E.29 A chemist measured out 8.61 g of copper(II) chloride tetrahydrate, CuCl2 4H2O. (a) How many moles of CuCl2 4H2O were measured out? (b) How many moles of Cl ions are present in the sample? (c) How many H2O molecules are present in the sample? d) What fraction of the total mass of the sample was due to oxygen?

For this question, I was just wondering how you would find the moles of Cl ions and the molecules of H20 present.

[Chem_Mod]

Consider the molar ratio of Cl- ions and H2O molecules in the compound

[Rachel Yu 1G]

It's relative to the moles of CuCl2 4H2O. For every mole of CuCl2 4H2O there are two moles of Cl- atoms because of Cl2. There would also be four moles of H2O for every mole of CuCl2 4H2O because of the stoichiometric coefficient "4" in 4H20. You can find the moles of Cl- and H2O in this problem by finding the moles of CuCl2 4H2O first. Then apply the molar ratios from before, so the moles of Cl- atoms is two times this amount and the moles of H2O would be four times.

[Camille 4I]

How would you determine the total mass of the sample due to oxygen? When I start with 0.042 moles of copper (II) chloride tetrahydrate, I identify that there are 4 moles H2O in 1 mole of copper (II) chloride tetrahydrate. Can I then proceed with identifying that there is 1 oxygen atom in H2O? How should I continue?