For the following reaction to occur: MgSO4 → Mg2+(aq) + SO42−(aq)?

Question

For the following reaction to occur



MgSO4 → Mg2+(aq) + SO42−(aq)



the change in enthalpy must be −91.3 kJ/mol



How much heat (kJ) is lost or gained by 241.0 ml of water when 3.43 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

Here are the basic concepts, you do the math

The enthalpy change has the following equation

q = m delta H. You already know that the delta H is -91.3. kJ /mol. You have the grams of MgSO4. Convert this to moles, multiply by the delta H and you have the heat released during this solution.

This is equal to the heat gained by the water. But the water gained heat, so the q is now positive, but equal to the heat from the reaction.

Now use q = m Cp delta T.

Cp of water is 4.184 J/goC.

You have the mass of water (1 ml = 1 g). All that's left is to solve for delta T.