How many degrees will the temperature of water, the mass of which is 20 kg, change, if 80% of all the energy released

How many degrees will the temperature of water, the mass of which is 20 kg, change, if 80% of all the energy released during the combustion of natural gas with a mass of 15 g is transferred to it?

Given:

m = 20 kilograms is the mass of water;

c = 4200 J / (kg * C) – specific heat capacity of water;

m1 = 15 grams = 0.015 kilograms is the mass of natural gas;

q = 46.1 * 10 ^ 6 J / kg – specific heat of combustion of natural gas;

n = 80% = 0.8 is the percentage of energy from the combustion of natural gas that is transferred to the water.

It is required to determine dt (degree Celsius) – how much the water temperature will increase.

When natural gas is burned, energy will be released equal to:

Q = q * m1.

According to the condition of the problem, energy will be transferred to heating the water:

Q1 = n * Q = n * q * m1.

Then the change in water temperature will be equal to:

dt = Q1 / (c * m) = n * q * m1 / (c * m) = 0.8 * 46.1 * 10 ^ 6 * 0.015 / (4200 * 20) = 553200/84000 = 6.6 ° Celsius.

Answer: The water temperature will increase by 6.6 ° Celsius.