For the following reaction to occur ?

Question

MgSO4 → Mg2+(aq) + SO42−(aq)

the change in enthalpy must be −91.3 kJ/mol



How much heat (kJ) is lost or gained by 309.0 ml of water when 5.40 g of MgSO4 is dissolved in the water ?

What is the change in temperature ( oC ) for the above process assuming no heat is lost or gained by the surroundings ?

Answer 1

A mole of MgSO4 = 78g

The experiment has 5.4/78 = moles 0.07 moles.

Specific heat of water is 4.19 g/jK

Change in enthalpy is +6300 J for the water = 4.19 * 309 * deltaT = +4.9 degs