Question

0.350 mol of a solid was dissolved in 260 mL of water at 21.2 oC. After the solid had fully dissolved, the final temperature of the solution was 26.5 oC. What is the molar heat of solution of the substance? kJ/mol

Answer 1

Answer: Heat of the solution  = mass water × specific heat water × change in temperature

mass water = 260ml (1.00g/ml ) = 260g

specific heat of water = c(water) = 4.184J/ g°C

Heat change of water = final temperature - initial temperature

                                       = 26.5 - 21.2

                                        = 5.3 °C

H = 260 g ( 4.184J/g°C ) (5.3°C) = 5765J

Molar heat = $\frac{5765J}{0.350mol}$

                    = 16473J/mol

Explanation: finding molar heat requires first to look at  specific heat of water and the change of water temperature