0.5 g of Ca is added to 50 mL of 1.0 M HCl. Once reaction is complete, the temperature of the solution has risen from 25.2 C to 71.4 C.

a. Calculate the heat gained by the solution.

b. heat lost by the reaction

c. calculate the heat of reacton.

I've gotten several answers and I think I am overthinking the question. I am having trouble finding the correct mass to use.

Let us assume that the solution has the same specific heat capacity as water, of 4.18 Joules per gram.

a) H = mCpΔT

Where m will be the mass of the solution. We do not incorporate the mass of Ca because it will dissolve and release some amount of Hydrogen gas; rendering its contribution negligible. Assuming solution density equal to water's 1 gram per cubic centimeter:

H = 50 x 4.18 x (71.4 - 25.2)

H = 9655.8 Joules are gained

b) Assuming no heat is lost to the surroundings,

Heat lost by reaction = Heat gained by soluton

Heat lost by reaction = 9655.8 Joules

c) Moles of Ca present = 0.5/40 = 0.0125

Heat of reaction is the energy released upon reaction of the quantities in the balanced equation of a reaction. In this case:

Ca + 2HCl → CaCl₂ + H₂

So 0.0125 moles produces 9655.8 Joules

1 mole will produce: 9655.8 / 0.0125

= 772.5 kJ