calculate the % H2O in each of the following hydrate compounds. Na2B4O7.10H2O,,,,,,,MgSO4.7H2O,,,,,CuSO4.5H2O

Question

please answer the questions if u can

Answer 1

Your question appears incomplete as there are some dots following the second compound. SO I will try to explain my reasoning

When you have a molecule written like

Na2B4O7.10H2O

it means that one molecule of sodium borate is surrounded by 10 molecules of H2O. I think you have been asked to calculate the percentage in mass, as that of the number of molecules is self explanatory (it would be about 91%!).

You need to know the molecular weight (MW) of your compounds:

MW (H20) = 18.015 g/mol
MW (Na2B4O7) = 200.9 g/mol and
MW (Na2B4O7.10H2O) = 381.37 g/mol
(this is Borax)

If you know consider having a mole of Borax, you know that the mass of H2O would account for 10 times its MW:
For 1mole of Na2B4O7.10H2O (mass = 381.37g), the mass H2O is 180.15g ====>
% mass H2O = 180.15/381.37 * 100 = 47.23 %

Similar reasoning with MgSO4.7H2O (Magnesium sulfate heptahydrate or Epsom salt):

MW (MgSO4) = 120.36 g/mol
MW (MgSO4.7H2O) = 246.48 g/mol

For each mole of MgSO4.7H2O:
mass H2O = 7*18.015 = 126.126 g

% H2O = 126.13/246.48 * 100 = 51.17%

Answer 2

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RE:
calculate the % H2O in each of the following hydrate compounds. Na2B4O7.10H2O,,,,,,,MgSO4.7H2O,,,,,CuSO4.5H2O
please answer the questions if u can

Answer 3

Calculate mass of water and divide by total mass.

Answer 4

%% water = Mass of water in sample/ molecular weight of compound x 100%

10H2O means 10 lots of water so the molecular mass of it is 10 x the molecular weight of water.