Question

What is the enthalpy change for the dissolution of 10 grams of NaCl in 100 mL of water at 25°C given that the enthalpy of solution of NaCl is -3.9 kJ/mol?

Answer 1

To calculate the enthalpy change for the dissolution of 10 grams of NaCl in 100 mL of water, we need to first determine the number of moles of NaCl and then use the enthalpy of solution to find the total enthalpy change.1. Calculate the number of moles of NaCl:The molar mass of NaCl = 58.44 g/mol  22.99 g/mol for Na + 35.45 g/mol for Cl Number of moles = mass / molar massNumber of moles = 10 g / 58.44 g/mol = 0.171 moles2. Calculate the enthalpy change:Enthalpy change = number of moles  enthalpy of solutionEnthalpy change = 0.171 moles   -3.9 kJ/mol  = -0.667 kJThe enthalpy change for the dissolution of 10 grams of NaCl in 100 mL of water at 25C is -0.667 kJ.