When 2.35g Mg(OH)2 is added to 250.0 mL of water, the temperature of the waterraises from 20.5oC to 36.0oC. Calculate the molar enthalpy of solution.

To calculate the molar enthalpy of solution, we need to follow these steps:

1. Calculate the heat absorbed by the water using the formula q = mcΔT, where m is the mass of the water, c is the specific heat capacity of water (4.18 J/g°C), and ΔT is the change in temperature.

   The mass of the water is approximately equal to the volume in mL (since the density of water is about 1 g/mL), so m = 250.0 g. The change in temperature ΔT = 36.0°C - 20.5°C = 15.5°C.

   So, q = (250.0 g)(4.18 J/g°C)(15.5°C) = 16227.5 J

2. Calculate the number of moles of Mg(OH)2. The molar mass of Mg(OH)2 is 58.32 g/mol.

   So, the number of moles = 2.35 g / 58.32 g/mol = 0.0403 mol

3. The molar enthalpy of solution is the heat absorbed per mole of solute. So, divide the heat absorbed by the number of moles to get the molar enthalpy of solution.

   ΔH = q / number of moles = 16227.5 J / 0.0403 mol = 402,500 J/mol

   Usually, enthalpy is expressed in kJ/mol, so divide by 1000 to convert: ΔH = 402.5 kJ/mol

So, the molar enthalpy of solution for Mg(OH)2 in this case is 402.5 kJ/mol.