Question

Calculate the percentage by mass of water in magnesium sulfate heptahydrate, MgSO4•7H2O

Answer 1

Answer:from reffered dfn of %by mass

%by M=mass of component particular/total mass

But mass directly proportional to Molar mass

% by M=molar mass of H2O cpn/total M

%by M=7((1×2)+16)/(7((1×2)+16)+(24+(16×4)+32))

=0.573

Answer 2

Answer:

The percentage  by mass of water in magnesium sulfate heptahydrate is 51.2 %

Explanation:

Step 1: Data given

Molar mass of MgSO4*7H2O = 246.5 g/mol

Molar mass of H2O = 18.02 g/mol

Molar massof MgSO4 = 120.37 g/mol

Step 2: Calculate % water in magnesium sulfate heptahydrate

Since we have 7 molecules of water in the heptahydrate, we will divide the molar mass of 7 molecules water by the molar mass of the heptahydrate.

m%(H2O) = (7*18.02)/ 246.5

m%(H2O) = (126.14 /246.5)*100%

m%(H2O) = 51.2 %

To controle this we will calculate the mass % of MgSO4

m%(MgSO4) = (120.37/ 246.50)*100%

m%(MgSO4) = 48.8%

51.2 + 48.8 = 100%

The percentage  by mass of water in magnesium sulfate heptahydrate is 51.2 %