Question

Для какого физического процесса потребуется большее количество теплоты: для нагревания воды от 20 до 100°С, или для превращения такой же массы воды в пар при 100°C? Масса воды 3кг

Answer 1

Для превращения в пар 3кг воды при 100 градусах потребуется Q=2,3*10^5*3=6,9*10^6Дж
для нагрева Q= cm(t2-t1)=4200*3*80=1008*10^3=10^6Дж
для испарения надо больше тепла в 6,9 раза

Answer 2

Comparison of Heat Required for Heating Water and Converting Water to Steam

To determine which process requires a greater amount of heat, let's compare the heat required for heating water from 20°C to 100°C and the heat required for converting the same mass of water to steam at 100°C.

Given: - Mass of water: 3 kg

Heat required to heat water from 20°C to 100°C: To calculate the heat required to heat water, we can use the formula:

Q = mcΔT

Where: - Q is the heat energy - m is the mass of the substance (water) - c is the specific heat capacity of the substance - ΔT is the change in temperature

The specific heat capacity of water is approximately 4.2 J/g°C.

Converting the mass of water from kg to g: - Mass of water = 3 kg = 3000 g

Using the formula, we can calculate the heat required to heat water from 20°C to 100°C:

Q1 = mcΔT = 3000 g * 4.2 J/g°C * (100°C - 20°C)

Q1 = 3000 g * 4.2 J/g°C * 80°C

Q1 = 1008000 J

Therefore, the heat required to heat water from 20°C to 100°C is approximately 1,008,000 J.

Heat required to convert water to steam at 100°C: To calculate the heat required to convert water to steam, we can use the formula:

Q = mL

Where: - Q is the heat energy - m is the mass of the substance (water) - L is the latent heat of vaporization

The latent heat of vaporization for water is approximately 2,260 kJ/kg.

Using the formula, we can calculate the heat required to convert the mass of water to steam:

Q2 = mL = 3000 g * 2.26 MJ/kg

Q2 = 6780000 J

Therefore, the heat required to convert the mass of water to steam at 100°C is approximately 6,780,000 J.

Conclusion:

Comparing the two processes, we find that the heat required to convert the same mass of water to steam at 100°C (approximately 6,780,000 J) is greater than the heat required to heat water from 20°C to 100°C (approximately 1,008,000 J). Therefore, converting the same mass of water to steam at 100°C requires a greater amount of heat.

Please note that the values provided are approximate and may vary slightly depending on the specific