Cold water was poured into a saucepan at a temperature of 10 degrees and put on an electric stove.

Cold water was poured into a saucepan at a temperature of 10 degrees and put on an electric stove. After 10 minutes, the water boiled. How long will it take for it to completely boil away?

t1 = 10 ° C.

t2 = 100 ° C.

T1 = 10 min = 600 s.

C = 4200 J / kg * ° C.

q = 2.3 * 10 ^ 6 J / kg.

T2 -?

The required amount of heat Qн for heating water is expressed by the formula: Qн = С * m * (t2 – t1).

Qн = N * T1.

We express the power of the tile by the formula: N = C * m * (t2 – t1) / T1.

The required amount of heat Qis for the evaporation of water is expressed by the formula: Qis = q * m. * (t2 – t1).

Qis = N * T2.

T2 = Qis / N = q * m * T1 / C * m * (t2 – t1) = q * T1 / C * (t2 – t1).

T2 = 2.3 * 10 ^ 6 J / kg * 600 s / 4200 J / kg * ° C * (100 ° C – 10 ° C) = 3650 s.

Answer: for complete evaporation of water, time T2 = 3650 s is required.