Answer
The molar mass for the Epsom salt is equal to 246.52g/mol.
Work Step by Step
According to the table 2.13, Epsom salt is $MgSO_4 $ hydrated with 7 $H_2O$ molecules.
$Mg:$ 24.31* 1 +
$S:$ 32.07* 1 +
$O:$ 16.00* 4
=120.38g/mol
And we have 7 water molecules with it:
$H_2O:$ $7 * (1.01(H) * 2 + 16.00 (O) * 1) = 7 * (18.02) = 126.14g/mol$
Adding those 2 molar masses:
$126.14 + 120.38 = 246.52g/mol$
