Energy is released when 100kg of steam at 150.0°C and standard pressure changes to water at 60.0°C. Calculate the total energy change.
Energy change= heat to cool steam to 100C + heat to change steam to water + heat change for water from 100 to 60c
To calculate the total energy change, we need to consider three stages:
1. Heat to cool steam to 100°C: We can use the specific heat capacity of steam to calculate the energy required to cool the steam from 150.0°C to 100.0°C. The specific heat capacity of steam is approximately 2.03 J/g°C.
The mass of the steam is 100 kg and the initial temperature is 150.0°C. Hence, the energy required is:
Energy = mass × specific heat capacity × temperature difference
Energy = 100,000 g × 2.03 J/g°C × (100.0°C - 150.0°C)
2. Heat to change steam to water: We need to account for the heat of vaporization (latent heat) required to change steam to water at 100.0°C. The heat of vaporization for water is approximately 2260 J/g.
The mass of the steam is 100 kg. Hence, the energy required is:
Energy = mass × latent heat
Energy = 100,000 g × 2260 J/g
3. Heat change for water from 100.0°C to 60.0°C: We can use the specific heat capacity of water to calculate the energy required to cool the water from 100.0°C to 60.0°C. The specific heat capacity of water is approximately 4.18 J/g°C.
The mass of the water is 100 kg. Hence, the energy required is:
Energy = mass × specific heat capacity × temperature difference
Energy = 100,000 g × 4.18 J/g°C × (100.0°C - 60.0°C)
To find the total energy change, we add up the energy values calculated in each stage:
Total Energy Change = Energy (cool steam to 100°C) + Energy (change steam to water) + Energy (cool water from 100°C to 60°C)