How much heat in KJ is needed to change 3.0 kg of ice at -10C into (superheated) steam at +150C ?
I will be happy to critique your thinking. Add the following heats:
heat to melt ice
heat to warm water to 100C
heat to change water to steam
heat to heat steam to 150C
heat to melt ice 2100 kj
liquid 4186 kj
steam 2010 kj
heat to heat steam 301.5 kj
To calculate the heat needed to change a substance from one phase to another, you need to consider multiple steps. In this case, you need to find the heat required to:
1. Raise the temperature of the ice from -10°C to 0°C (melting point of ice).
2. Melt the ice at 0°C into liquid water at 0°C.
3. Raise the temperature of the liquid water from 0°C to 100°C (boiling point of water).
4. Vaporize the liquid water at 100°C into steam at 100°C.
5. Raise the temperature of the steam from 100°C to 150°C.
Let's go through the calculations step by step:
1. To raise the temperature of the ice from -10°C to 0°C, you need to consider the specific heat capacity of ice. The specific heat capacity of ice is approximately 2.093 J/g°C.
- First, convert the mass of ice from kilograms to grams: 3.0 kg = 3,000 g.
- Calculate the heat required: Q1 = mass × specific heat capacity × change in temperature = 3,000 g × 2.093 J/g°C × (0°C - (-10°C)).
2. To melt the ice at 0°C into liquid water at 0°C, you need to consider the heat of fusion of ice. The heat of fusion of ice is 334 J/g.
- Calculate the heat required: Q2 = mass × heat of fusion = 3,000 g × 334 J/g.
3. To raise the temperature of liquid water from 0°C to 100°C, you need to consider the specific heat capacity of water. The specific heat capacity of water is approximately 4.186 J/g°C.
- Calculate the heat required: Q3 = mass × specific heat capacity × change in temperature = 3,000 g × 4.186 J/g°C × (100°C - 0°C).
4. To vaporize the liquid water at 100°C into steam at 100°C, you need to consider the heat of vaporization of water. The heat of vaporization of water is 2260 J/g.
- Calculate the heat required: Q4 = mass × heat of vaporization = 3,000 g × 2260 J/g.
5. To raise the temperature of the steam from 100°C to 150°C, you need to consider the specific heat capacity of steam. The specific heat capacity of steam is approximately 2.03 J/g°C.
- Calculate the heat required: Q5 = mass × specific heat capacity × change in temperature = 3,000 g × 2.03 J/g°C × (150°C - 100°C).
Finally, add up all the calculated heat values to find the total heat required:
Total heat required = Q1 + Q2 + Q3 + Q4 + Q5.
Simply substitute the values into the equations and perform the calculations to find the final answer in kilojoules (kJ).