To calculate the molar mass of sodium sulfate decahydrate Na2SO410H2O , we need to find the molar mass of each element in the compound and then add them together.1. Sodium Na : There are 2 sodium atoms in the compound. The molar mass of sodium is 22.99 g/mol. Molar mass of 2 Na = 2 22.99 g/mol = 45.98 g/mol2. Sulfur S : There is 1 sulfur atom in the compound. The molar mass of sulfur is 32.07 g/mol. Molar mass of S = 1 32.07 g/mol = 32.07 g/mol3. Oxygen O : There are 4 oxygen atoms in the sulfate ion SO4 and 20 oxygen atoms in the 10 water molecules 10H2O . The molar mass of oxygen is 16.00 g/mol. Molar mass of 24 O = 24 16.00 g/mol = 384.00 g/mol4. Hydrogen H : There are 20 hydrogen atoms in the 10 water molecules 10H2O . The molar mass of hydrogen is 1.01 g/mol. Molar mass of 20 H = 20 1.01 g/mol = 20.20 g/molNow, add the molar masses of all the elements together:Molar mass of Na2SO410H2O = 45.98 g/mol Na + 32.07 g/mol S + 384.00 g/mol O + 20.20 g/mol H = 482.25 g/molSo, the molar mass of sodium sulfate decahydrate Na2SO410H2O is 482.25 g/mol.