How much the rest mass of the combustion products of 5 kg of coal differs from the rest mass

How much the rest mass of the combustion products of 5 kg of coal differs from the rest mass of the substances that have reacted.

Specific heat of combustion of coal – Qsp. combustion. (C) = 2.7 * 10 ^ 7 J / kg.

When burned, 5 kg of coal will be released in the form of energy:

E = Qsp. combustion. (C) * m (C) = 2.7 * 10 ^ 7 * 5 = 1.35 * 10 ^ 8 J.

Let us find the decrease in the mass of the reaction products:

Δm = E / c2 = (1.35 * 10 ^ 8) / (3 * 10 ^ 8) ^ 2 = 1.5 * 10 ^ -9 kg = 1.5 μg.

Answer: Δm = 1.5 μg.