Question

Сколько воды можно нагреть от 10 °C до 50 °С, если на ее нагревание пошла половина энергии, полученной в результате сгорания 10 кг каменного угля? Распишите все дано и решение пожалуйста.

Answer 1

Ответ:

Чтобы вычислить массу воды, нагретой за счет сгорания каменного угля, воспользуемся формулой: η = Св * mв * (t2 - t1) / (qу * mу) и mв = η * qу * mу / (Св * (t2 - t1)).

Постоянные и переменные: η — КПД процесса (η = 50% = 0,5); qу — уд. теплота сгорания угля (qу = 2,7 * 107 Дж/кг); mу — масса угля (mу = 40 кг); Cв — уд. теплоемкость воды (Cв = 4200 Дж/(кг*К)); t2 — кон. темп. (tк = 60 ºС); t1 — темп. до нагревания (t1 = 10 ºC).

Расчет: mв = 0,5 * 2,7 * 107 * 40 / (4200 * (60 - 10)) = 2571,4 кг. Вроде так если нет то сорри

Answer 2

Given:

- Initial temperature of water: 10 °C - Final temperature of water: 50 °C - Energy obtained from burning 10 kg of coal: half of the total energy

Solution:

To calculate the amount of water that can be heated from 10 °C to 50 °C, we need to consider the energy obtained from burning 10 kg of coal.

First, let's find the total energy obtained from burning 10 kg of coal. Since we know that half of this energy is used to heat the water, we can calculate the total energy as follows:

Total energy = Energy used to heat the water + Energy not used to heat the water

Since half of the energy is used to heat the water, we can write the equation as:

Total energy = Energy used to heat the water + (1/2) * Total energy

Simplifying the equation, we get:

(1/2) * Total energy = Energy used to heat the water

Now, let's find the energy used to heat the water. The energy required to heat a substance can be calculated using the formula:

Energy = mass * specific heat capacity * temperature change

In this case, the mass of water is unknown, but we can assume it to be 1 kg for simplicity. Therefore, the energy used to heat the water can be calculated as:

Energy used to heat the water = 1 kg * specific heat capacity * temperature change

The specific heat capacity of water is approximately 4.18 J/g°C.

Now, let's substitute the values into the equation:

(1/2) * Total energy = 1 kg * 4.18 J/g°C * temperature change

Simplifying further:

(1/2) * Total energy = 4.18 J/°C * temperature change

Finally, let's solve for the temperature change:

temperature change = (1/2) * Total energy / (4.18 J/°C)

Now, we can substitute the given values into the equation to find the temperature change:

temperature change = (1/2) * Total energy / (4.18 J/°C) = (1/2) * (Energy obtained from burning 10 kg of coal) / (4.18 J/°C)

Please note that the specific heat capacity of water is given in joules per gram per degree Celsius (J/g°C), so we need to convert the mass of water from kilograms to grams.

Since the specific values for the energy obtained from burning 10 kg of coal and the specific heat capacity of water are not provided, we cannot calculate the exact temperature change or the amount of water that can be heated.