Question

Какое количество теплоты выделится при конденсации водяного пара массой 10 кг при 100 С и охлаждении образовавшейся воды до 20 С?

Answer 1

10*2300=23 000 Дж при конденсации выделится 

10*4200*(20-100)=-336 000 Дж (минус отпрасываем он указывает на охлаждение)

23 000+336 000=359 000 Дж или 359кДж

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Answer 2

Calculation of Heat Released during Condensation

To calculate the amount of heat released during the condensation of water vapor, we can use the formula:

Q = m * (h2 - h1)

Where: - Q is the heat released (in joules) - m is the mass of water vapor (in kilograms) - h2 is the specific enthalpy of liquid water at the final temperature (in joules per kilogram) - h1 is the specific enthalpy of water vapor at the initial temperature (in joules per kilogram)

In this case, we have: - m = 10 kg (mass of water vapor) - h1 = ? (specific enthalpy of water vapor at 100°C) - h2 = ? (specific enthalpy of liquid water at 20°C)

To find the specific enthalpies, we can refer to steam tables or thermodynamic charts. Unfortunately, the search results did not provide the specific enthalpies directly. However, we can still proceed with the calculation using the given temperatures and assume constant specific heat capacities.

Assumption of Constant Specific Heat Capacity

Since we don't have the specific enthalpies, we can make an assumption that the specific heat capacity of water vapor and liquid water remains constant over the given temperature range. This assumption allows us to use the specific heat capacity of water to calculate the heat released during condensation.

The specific heat capacity of water is approximately 4186 J/kg°C.

Using this assumption, we can calculate the heat released during condensation as follows:

1. Calculate the heat absorbed by the water vapor to cool it from 100°C to 20°C: - Q1 = m * c * (t1 - t2) - Where: - Q1 is the heat absorbed (in joules) - m is the mass of water vapor (in kilograms) - c is the specific heat capacity of water (in joules per kilogram per degree Celsius) - t1 is the initial temperature (in degrees Celsius) - t2 is the final temperature (in degrees Celsius)

Plugging in the values: - Q1 = 10 kg * 4186 J/kg°C * (100°C - 20°C)

2. Calculate the heat released during condensation: - Q2 = m * c * (t2 - t3) - Where: - Q2 is the heat released (in joules) - m is the mass of water vapor (in kilograms) - c is the specific heat capacity of water (in joules per kilogram per degree Celsius) - t2 is the initial temperature (in degrees Celsius) - t3 is the final temperature (in degrees Celsius)

Plugging in the values: - Q2 = 10 kg * 4186 J/kg°C * (20°C - 0°C)

3. Calculate the total heat released during condensation: - Q_total = Q1 + Q2

Let's calculate the values:

1. Calculate Q1: - Q1 = 10 kg * 4186 J/kg°C * (100°C - 20°C)

2. Calculate Q2: - Q2 = 10 kg * 4186 J/kg°C * (20°C - 0°C)

3. Calculate Q_total: - Q_total = Q1 + Q2

Calculation:

1. Calculate Q1: - Q1 = 10 kg * 4186 J/kg°C * (100°C - 20°C) - Q1 = 10 kg * 4186 J/kg°C * 80°C - Q1 = 3348800 J

2. Calculate Q2: - Q2 = 10 kg * 4186 J/kg°C * (20°C - 0°C) - Q2 = 10 kg * 4186 J/kg°C * 20°C - Q2 = 837200 J

3. Calculate Q_total: - Q_total = Q1 + Q2 - Q_total = 3348800 J + 837200 J - Q_total = 4186000 J

Therefore, the total amount of heat released during the condensation of 10 kg of water vapor from 100°C to 20°C is 4,186,000 joules.

Please note that this calculation assumes constant specific heat capacities and does not take into account any phase changes that may occur during the condensation process.