20ml of 0.5M NaOH = 20 × 0.5 = 10 milli moles = 10 milli equivalents 100ml of 0.1M HCl = 100 × 0.1 = 10 milli moles = 10 milli equivalents 10 milli equivalents on neutralisation give heat = x kJ 1 g.eq = 1000 milli eq. will give = 100 x kJ ΔH = - 100 x kJ