1)The mass percent of water in a hydrate of MnCl2 is 36.41%. What is the empirical formula of the hydrate?

Question

2) A 4.00 g sample of a hydrate of nickel (iii) bromide losses 0.793 g of water when heated. Determine mass percentage of water in the hydrate and the formula of the hydrate. 3) A hydrated compound has analysis of 18.29% ca, 32.37 % Cl and 49.34 % H2O .What is its formula? 4) the masses of the hydrates listed below were measured, heated to drive off the water of hydration, and cooled. Then the masses of the residues were measured. Find the formulas of the following hydrates.a) 1.04 g Ni SO4.n H20 gave a residue of 0,61g b) 1.26 g CaSO4. n H2O gave a residue of 0.99g
4) A 2.50 g sample of hydrate of calcium sulfate losses 0.523g of water when heated. Determine the mass percent of water in the hydrate and the formula of the hydrate.
Can someone help me? thanks

Answer 1

In all of these divide the mass (or percentage) of water by 18, and work out the moles of the rest of the compound by dividing by its Mr (for example of MnCl2). You will get two numbers, which are moles of compound and moles of water. Now just divide the larger by the smaller, and that is the number of molecules of water in the formula of the compound.