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
