## Chemistry and Chemical Reactivity (9th Edition)

Molar masses (g/mol): $MgSO_4: 120.37g/mol,\ H_2O:18.02,\ MgSO_4\dot{}7\ H_2O: 246.47$ Mass of epsom salt: 1.394g Mass of the product: 0.885g Mass of lost water 1.394- 0.885= 0.509g Number of moles: $MgSO_4\dot{}7\ H_2O$: $1.394/246.47=5.66\times10^{-3}\ mol$ lost $H_2O$: $0.509/18.02=0.0282\ mol$ Ratio of the number of moles of lost $H_2O$ by $MgSO_4\dot{}7\ H_2O$: $0.0282\div5.66\times10^{-3} = 4.99$ 5 moles of hydration water are lost per mole of epsom salt: Final molecular formula: $MgSO_4\dot{}2\ H_2O$ The value of x is 2.