Question

Chemistry question!! What is the percent by mass of water in the hydrate CoCl2 X 6H2O?

Answer 1

well the mass of cobalt(II) chloride is 129,839 g/mol
The mass of water (H2O) is 18,015 g/mol
So hexahydrage (6H2O) is 108,092 g/mol

Adding the weight of hexahydrage to cobalt(II)chloride = 237,931 g/mol

Now 237,931 is 100%
how many is 108,092?

You can find all molecular weights in a periodic table like www.ptable.com