Question

Calculate the enthalpy change for the dissolution of 10.0 grams of sodium chloride (NaCl) in 100 mL of water at 25°C. The density of water is 1.00 g/mL and the heat capacity of the solution is 4.18 J/g°C. The molar mass of NaCl is 58.44 g/mol and its enthalpy of dissolution is -3.9 kJ/mol.

Answer 1

To calculate the enthalpy change for the dissolution of 10.0 grams of sodium chloride  NaCl  in 100 mL of water at 25C, we will first determine the number of moles of NaCl and then use the enthalpy of dissolution to find the total enthalpy change.1. Calculate the number of moles of NaCl:moles of NaCl = mass of NaCl / molar mass of NaClmoles of NaCl = 10.0 g / 58.44 g/molmoles of NaCl = 0.171 mol2. Calculate the enthalpy change for the dissolution of NaCl:enthalpy change = moles of NaCl * enthalpy of dissolutionenthalpy change = 0.171 mol *  -3.9 kJ/mol enthalpy change = -0.667 kJThe enthalpy change for the dissolution of 10.0 grams of sodium chloride in 100 mL of water at 25C is -0.667 kJ.