Question

Calculate the amount of heat energy released when 50 mL of 1 M hydrochloric acid (HCl) is mixed with 50 mL of 1 M sodium hydroxide (NaOH) solution. The heat of neutralization for the reaction between HCl and NaOH is -57.1 kJ/mol.

Answer 1

To calculate the heat energy released, we first need to determine the number of moles of HCl and NaOH reacting. Since both solutions have the same concentration and volume, they will react in a 1:1 ratio.Moles of HCl =  concentration of HCl    volume of HCl Moles of HCl =  1 mol/L    50 mL   1 L/1000 mL  Moles of HCl = 0.05 molMoles of NaOH =  concentration of NaOH    volume of NaOH Moles of NaOH =  1 mol/L    50 mL   1 L/1000 mL  Moles of NaOH = 0.05 molNow that we have the moles of both reactants, we can calculate the heat energy released using the heat of neutralization.Heat energy released =  moles of HCl    heat of neutralization Heat energy released =  0.05 mol    -57.1 kJ/mol Heat energy released = -2.855 kJThe negative sign indicates that the reaction is exothermic, meaning that it releases heat. Therefore, 2.855 kJ of heat energy is released when 50 mL of 1 M HCl is mixed with 50 mL of 1 M NaOH.