When 100 mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pres

Question

When 100 mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pressure, a temperature increase of $5.7^{\circ} \mathrm{C}$ was measured for the beaker and its contents (expt. 1). Because the enthalpy of neutralisation of a strong acid with a strong base is a constant ( $-57.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$ ), this experiment could be used to measure the calorimeter constant.
In a second experiment (expt. 2), 100 mL of 2.0 M acetic acid $\left(K_a=2.0 	imes 10^{-5}ight)$ was mixed with 100 mL of 1.0 M NaOH (under identical conditions to expt. 1) where a temperature rise of $5.6^{\circ} \mathrm{C}$ was measured.
(Consider heat capacity of all solutions as $4.2 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}$ and density of all solutions as $1.0 \mathrm{~g} \mathrm{~mL}^{-1}$ )

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