Question

На печь поставили кастрюлю с 3 л воды при 100 °С. Сколько каменного угля надо сжечь, чтобы испарить всю воду? КПД печи 45%. ответ должен быть 56,8 кг

Answer 1

Ответ:

Объяснение:

m₁=3 кг

t=100°C

η=0,45

q=27·10⁶Дж/кг

L=2,3·10⁶Дж/кг

m₂-?

qm₂η=m₁L

m₂=m₁L/qη

m₂=3·2,3·10⁶/27·10⁶·0,45=0,567 (кг)

Извини, друг, твой ответ точно неправильный, ведь не может быть затрачено 56, 8 кг угля на испарение каких-то 3 л воды

Answer 2

C воды= 4200 дж/кг*С.

Кпд= (q нужная/ q затраченная) *100%

q угля= 27*107

m воды=3литра

t1=100

Кпд=45%=0.45

Решение:

0.45=(3*4200)/2,7*107*m

2,7*107m = (3*4200)/0.45

2,7*107m= 28000

m= 2,8*104/2,7*107=0.001кг угля

Answer 3

Calculation of the amount of coal needed to evaporate all the water

To calculate the amount of coal needed to evaporate all the water, we need to consider the energy required to heat the water to its boiling point and then to convert it from liquid to vapor. We can use the specific heat capacity of water and the heat of vaporization to perform the calculation.

Given: - Amount of water = 3 liters - Initial temperature of water = 100 °C - Efficiency (KPD) of the stove = 45%

To calculate the amount of coal needed, we can follow these steps:

1. Calculate the energy required to heat the water to its boiling point: - Specific heat capacity of water = 4.18 J/g°C - Density of water = 1 g/mL - Mass of water = volume × density = 3 liters × 1 g/mL = 3000 grams - Energy required = mass × specific heat capacity × temperature difference - Temperature difference = boiling point - initial temperature = 100 °C - 0 °C = 100 °C - Energy required to heat the water = 3000 grams × 4.18 J/g°C × 100 °C = 1,254,000 J

2. Calculate the energy required to convert the water from liquid to vapor: - Heat of vaporization of water = 2260 J/g - Energy required to vaporize the water = mass × heat of vaporization - Energy required to vaporize the water = 3000 grams × 2260 J/g = 6,780,000 J

3. Calculate the total energy required: - Total energy required = energy to heat the water + energy to vaporize the water - Total energy required = 1,254,000 J + 6,780,000 J = 8,034,000 J

4. Calculate the energy output of the stove: - Efficiency (KPD) of the stove = 45% - Energy output of the stove = total energy required / efficiency - Energy output of the stove = 8,034,000 J / 0.45 = 17,853,333.33 J

5. Calculate the amount of coal needed: - Heat value of coal = 24,000,000 J/kg (assumed value) - Amount of coal needed = energy output of the stove / heat value of coal - Amount of coal needed = 17,853,333.33 J / 24,000,000 J/kg = 0.7438888889 kg

Therefore, the amount of coal needed to evaporate all the water is approximately 0.744 kg.

Please note that the calculation assumes an assumed heat value of coal and does not take into account other factors such as heat losses during combustion.