How many kilo calories (kcal) are required to change 1 kg of 100°C boiling water to 100°C steam?
To calculate the amount of kilocalories (kcal) required to change 1 kg of 100°C boiling water to 100°C steam, we need to consider the specific heat capacity of water, the latent heat of vaporization, and the mass of water.
1. Start by calculating the energy required to raise the temperature of water from 0°C to the boiling point, which is 100°C. The specific heat capacity of water is about 4.18 J/g°C.
Thus, to calculate the energy required to raise the temperature of 1 kg of water by 100°C:
Energy = mass × specific heat capacity × temperature change
Energy = 1,000 g × 4.18 J/g°C × 100°C
Note: We have converted the mass from 1 kg to 1,000 g because the specific heat capacity is given in grams.
2. Next, calculate the energy required for the phase change from liquid (water) to gas (steam). The latent heat of vaporization for water is approximately 540 calories (depending on the altitude and other factors).
To convert calories to kilocalories, divide by 1,000:
Latent heat of vaporization = 540 calories / 1,000
3. Now, convert the result from step 2 to Joules by multiplying by 4.18:
Energy = Latent heat of vaporization × mass
4. Lastly, since we want the answer in kilocalories, divide the energy obtained in step 3 by 4.18:
Energy in kilocalories = Energy in Joules / 4.18
By following these steps, you should be able to calculate the amount of kilocalories required to change 1 kg of 100°C boiling water to 100°C steam.