Determine the quantity (g) of pure MgSO4 in 2.4 g of MgSO4•7H2O. Show your work.

Answer 1

Molar mass MgSO₄•7H₂O = 246.5 g / mole

Atomic mass Mg = 24.3 g /mol

% Mg in MgSO₄•7H₂O = 24.3 g / 246.5 g (x100%) = 9.86% Mg

2.4 g MgSO₄•7H₂O x 9.86% Mg = 0.24 g Mg (2 sig. figs.)