Water was boiled in a kettle on a gas stove for 15 minutes. What mass of gas burns out in 1 second if the kettle contains

Water was boiled in a kettle on a gas stove for 15 minutes. What mass of gas burns out in 1 second if the kettle contains 3 liters of water at a temperature of 20 degrees Celsius?

T1 = 15 min = 900 s.

V = 3 l = 3 * 10 ^ -3 m3.

C = 4200 J / kg * ° C.

ρ = 1000 kg / m3.

t1 = 20 ° C.

t2 = 100 ° C.

T2 = 1 s.

q = 4.4 * 10 ^ 7 J / kg.

mg -?

The amount of thermal energy that is released during the combustion of gas Qg goes to heating water Qw: Qg = Qw.

Qw = C * mw * (t2 – t1) = C * ρ * V * (t2 – t1).

Qg = q * mg * T1.

C * ρ * V * (t2 – t1) = q * mg * T1.

mg = C * ρ * V * (t2 – t1) / q * T1.

mg = 4200 J / kg * ° C * 1000 kg / m3 * 3 * 10 ^ -3 m3 * (100 ° C – 20 ° C) / 4, 4 * 10 ^ 7 J / kg * 900 s = 254.5 * 10 ^ -7 kg.

Answer: in a gas stove for 1 s, a gas with a mass of mg = 254.5 * 10 ^ -7 kg burns.