Question

Сколько энергии надо затратить, чтобы превратить в пар 1 кг воды, начальная температура которой 25°С?

Answer 1

На нагрев 1 литра или 1 кг воды на 1 градус С нужно затратить 4200 Дж. На нагрев с 25 до 100 градусов нужно затратиь 4200*75=315000 Дж или 315 кДж

Answer 2

Calculating the energy needed to heat 1 kg of water from 25°C to its boiling point

The amount of energy needed to convert 1 kg of water at 25°C into steam is 2,257 kJ.

When water is heated, it absorbs heat energy which causes its temperature to rise. At 0°C, water has a phase change from solid ice to liquid water, which is called melting or fusion. At 100°C, water undergoes another phase change from liquid to gas (steam), which is called vaporization or boiling.

To calculate the energy needed for this process, we use the specific heat capacity of water and the heat of vaporization. Water has a specific heat capacity of 4.184 kJ/kg°C. This means it takes 4.184 kJ of energy to raise the temperature of 1 kg of water by 1°C.

The heat of vaporization of water is 2,257 kJ/kg. This is the amount of energy required to convert 1 kg of liquid water at its boiling point into water vapor (steam) at the same temperature, without changing the temperature.

So to calculate the total energy needed: - Raise the temperature from 25°C to 100°C: (100 - 25) * 4.184 = 1,534.8 kJ - Convert to vapor: 2,257 kJ - Total energy = 1,534.8 kJ + 2,257 kJ = 2,257 kJ

Therefore, the total amount of energy needed to convert 1 kg of water at 25°C into steam is 2,257 kJ.