First, we need to calculate the moles of magnesium sulfate heptahydrate:moles = mass / molar massmoles = 5.00 g / 246.48 g/molmoles = 0.0203 molNext, we need to calculate the heat absorbed by the water:q = mcTq = 100.0 g 4.18 J/gC 30.0C - 25.0C q = 100.0 g 4.18 J/gC 5.0C q = 2090 JNow, we can calculate the heat of hydration per mole of magnesium sulfate heptahydrate:heat of hydration = q / molesheat of hydration = 2090 J / 0.0203 molheat of hydration = 102,964 J/molThe heat of hydration for the dissolution of 5.00 grams of magnesium sulfate heptahydrate in 100.0 grams of water is approximately 102,964 J/mol.