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

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 °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 kJ 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 (K_a = 2.0 × 10^–5) was mixed with 100 mL of 1.0 M NaOH (under identical conditions to expt. 1) where a temperature rise of 5.6 °C was measured.
(Consider heat capacity of all solutions as 4.2 J g^–1 K^–1 and density of all solutions as 1.0 g mL^–1)

The pH of the solution after expt. 2 is