Calculate energy of combustion of methanol?

Question

Calculate the energy of combustion per gram of Methanol (kJ/g) if 29.7 mL of water is placed in the test tube and the temperature changes from 22.9 °C to 51.1°C. The initial mass of the spirit burner is 239.39 g and the final mass is 238.79 g. State your answer with correct significant digits.

I got 5.84 kJ/g as my final answer assuming water has C = 4.19J/g

Answer 1

q = m c ΔT

Assuming density of water is 1 g/mL, then 29.7 mL = 29.7 g

q_H2O = 29.7 g x 4.19 J / °C g x (51.1 - 22.9 °C) = 3509 J ≅ 3.509 kJ ≈ 3.51 kJ (rounded to 3 significant figures)

q_H2O = −q_methanol since methanol is combusting and producing heat, therefore, q_methanol is negative 3.51 kJ.

mass of methanol undergoing combustion = 239.39 - 238.79 = 0.60 g

Energy of combustion = −3.51 kJ / 0.60 g = −5.85 kJ/g