Question

A student needs to calculate the heat of mixing for a 50 mL solution containing 0.1 M HCl and 0.1 M NaOH. The temperature of the solution is 25°C and the density is 1 g/mL. The enthalpy of neutralization for HCl and NaOH is -57.3 kJ/mol. Determine the heat of mixing for the solution.

Answer 1

To calculate the heat of mixing for the solution, we first need to determine the number of moles of HCl and NaOH in the solution.1. Calculate the moles of HCl and NaOH in the solution:Moles of HCl =  Volume of solution  x  Concentration of HCl Moles of HCl =  50 mL  x  0.1 mol/L  = 0.005 molMoles of NaOH =  Volume of solution  x  Concentration of NaOH Moles of NaOH =  50 mL  x  0.1 mol/L  = 0.005 mol2. Determine the limiting reactant:Since both HCl and NaOH have the same number of moles  0.005 mol , they will react completely with each other, and there will be no excess reactant.3. Calculate the heat of mixing using the enthalpy of neutralization:Heat of mixing =  Moles of limiting reactant  x  Enthalpy of neutralization Heat of mixing =  0.005 mol  x  -57.3 kJ/mol  = -0.2865 kJThe heat of mixing for the 50 mL solution containing 0.1 M HCl and 0.1 M NaOH is -0.2865 kJ.