On an alcohol lamp, 300 g of water was heated from 15 to 75 degrees Celsius.

On an alcohol lamp, 300 g of water was heated from 15 to 75 degrees Celsius. Determine the efficiency of heating if 8 g of alcohol was consumed for heating.

Initial data: m1 (mass of heated water) = 300 g = 0.3 kg; t (water temperature before heating) = 15 ºС; t1 (water temperature after heating) = 75 ºС; m2 (mass of consumed alcohol) = 8 g = 8 * 10 ^ -3 kg.

Reference data: C (specific heat capacity of water) = 4200 J / (kg * K); q (specific heat of combustion of alcohol) = 27 * 10 ^ 6 J / kg.

The efficiency of the spirit lamp is determined by the formula: η = Qp / Qz = C * m1 * (t1 – t) / (q * m2).

Let’s calculate: η = 4200 * 0.3 * (75 – 15) / (27 * 10 ^ 6 * 8 * 10 ^ -3) = 0.35 or 35%.