A calorimeter contains 280.0g of water at 13.5C. When 0.250g of a substance with a molar mass of 510.0g/mol is dissolved, the temperature of the resultant solution increases to 17.5C. Assume that the specific heat and density of the resulting solution are equal to those of water, 4.18J/gC and 1.00 g/mL, respectively and assume that no heat is lost to the calorimeter itself, nor to the surroundings. Calculate the amount of heat in Joules released by dissolving the substance.

Question

Arias

Chemistry

27 September, 13:51

A calorimeter contains 280.0g of water at 13.5C. When 0.250g of a substance with a molar mass of 510.0g/mol is dissolved, the temperature of the resultant solution increases to 17.5C. Assume that the specific heat and density of the resulting solution are equal to those of water, 4.18J/gC and 1.00 g/mL, respectively and assume that no heat is lost to the calorimeter itself, nor to the surroundings. Calculate the amount of heat in Joules released by dissolving the substance.

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Matthias Humphrey · Answer 1

The change in heat is simply equal to:

change in heat ΔH = final enthalpy - initial enthalpy

ΔH = [280.25 g * 4.18J/gC * (17.5°C) ] - [280 g * 4.18J/gC * 13.5°C]

ΔH = 4,699.89 J = 4.7 kJ

Hence heat released is about 4.7 kJ