1. Find the molar mass of each component:
* MgSO₄:
* Mg: 24.31 g/mol
* S: 32.06 g/mol
* O: 16.00 g/mol (x 4) = 64.00 g/mol
* Total molar mass of MgSO₄ = 24.31 + 32.06 + 64.00 = 120.37 g/mol
* 7H₂O:
* H: 1.01 g/mol (x 2 x 7) = 14.14 g/mol
* O: 16.00 g/mol (x 7) = 112.00 g/mol
* Total molar mass of 7H₂O = 14.14 + 112.00 = 126.14 g/mol
2. Find the total molar mass of Epsom salt:
* Total molar mass of MgSO₄·7H₂O = 120.37 g/mol + 126.14 g/mol = 246.51 g/mol
3. Calculate the percent by mass of water:
* (Mass of water / Total mass of Epsom salt) x 100%
* (126.14 g/mol / 246.51 g/mol) x 100% = 51.17%
Therefore, the percent by mass of water in Epsom salt (MgSO₄·7H₂O) is approximately 51.17%.
