The salt magnesium chloride is soluble in water. When 0.620 g MgCl2 is dissolved in 112.00 g water, the temperature of the solution increases from 25.00 °C to 27.33 °C. Based on this observation, calculate the dissolution enthalpy, ΔdissH, of MgCl2. Assume that the specific heat capacity of the solution is 4.184 J g-1 °C-1 and that the energy transfer to the calorimeter is negligible. ΔdissH = kJ/mol

The enthalpy of the dissociation of the magnesium chloride is -168.2 kJ/mol.

Explanation:

Mass of magnesium chloride = 0.620 g

Moles of magnesium chloride =

Mass of water = 112.00 g

Mass of solution, m = 0.62 g + 112 g =112.62 g

Heat capacity of the solution = c =

Initial temperature of the solution =

Final temperature of the solution =

Heat gained by solution = Q

Q = 1,097.90 J =1.09790 kJ ≈ 1.098 kJ

Enthalpy of the dissociation magnesium chloride :

The enthalpy of the dissociation of the magnesium chloride is -168.2 kJ/mol.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

it is stable as it is in group 0 which have full outer shells of electrons