Question

What is the enthalpy change for dissolving 10 grams of sodium chloride (NaCl) in 200 mL of water at 25°C if the final temperature of the solution is 30°C? Given: the enthalpy of solution for NaCl is -3.9 kJ/mol.

Answer 1

To calculate the enthalpy change for dissolving 10 grams of NaCl in 200 mL of water, we first need to determine the number of moles of NaCl and then use the given enthalpy of solution.1. Calculate the number of moles of NaCl:Molecular weight of NaCl = 58.44 g/mol  22.99 g/mol for Na + 35.45 g/mol for Cl 10 g NaCl / 58.44 g/mol = 0.1712 mol NaCl2. Calculate the enthalpy change for dissolving NaCl:Enthalpy change = moles of NaCl  enthalpy of solution per moleEnthalpy change = 0.1712 mol   -3.9 kJ/mol  = -0.66768 kJThe enthalpy change for dissolving 10 grams of sodium chloride in 200 mL of water at 25C is -0.66768 kJ.