Answer to Question #133311 in Organic Chemistry for Tatiana

Question

When 2.35g of Mg(OH)2 is added to 250.0 mL of water, the temperature of the water raises from 20.5°C to 36.0°C. Calculate the molar enthalpy of solution.

Answer 1

M(Mg(OH)₂) = 24.3 +16*2 + 2 = 58.3

n(Mg(OH)₂) = 2.35 / 58.3 = 0.04 mol

Q = C_p(H₂O) * (T₂ - T₁)*m(H₂O) =  4179.6 * (36 - 20.5) * 0.25 = 16195.95 J

H_solution= 16195.95 / 0.04 = 404898.75 J/mol = 404.9 kJ/mol