Final answer:
The student's theoretical yield of KCl is 0.0500 mol. The heat absorbed (q_solution) by the solution is 2.687 kJ. The student's calculated enthalpy change (ΔH_rxn) is 53.74 kJ/mol, which results in a percent error of 196.59% compared to the theoretical value of ΔH_rxn, which is -55.8 kJ/mol.
Step-by-step explanation:
1. The theoretical yield of KCl is determined by the stoichiometry of the reaction. Since both HCl and KOH are present in equal molar amounts, they will react in a 1:1 ratio according to the chemical equation HCl (aq) + KOH (aq) --> KCl (aq) + H2O (l). With 0.0500 mol of each reactant (calculated from the 50.0 mL of 1.00 M solutions), the theoretical yield of KCl is also 0.0500 mol.
2. To calculate the heat absorbed (qsolution) by the solution, use the formula q = m•c•ΔT, where m is the mass of the solution, c is the specific heat capacity (4.184 J/g°C for water), and ΔT is the change in temperature. Here, q = 100.2 g • 4.184 J/g°C • (31.43°C - 25.00°C) = 2686.892 J or 2.687 kJ.
3. To find the enthalpy change (ΔHrxn) per mole of KCl, divide the heat absorbed by the moles of KCl formed. ΔHrxn = 2.687 kJ / 0.0500 mol = 53.74 kJ/mol.
4. To calculate the percent error in the student's determination of ΔHrxn, use the formula: percent error = |(experimental value - theoretical value) / theoretical value| • 100%. Here, the percent error = |(53.74 kJ/mol)- (-55.8 kJ/mol)| / (-55.8 kJ/mol) • 100% = 196.59%.