Understanding the Process
Boiling water involves two steps:
1. Heating the water from its initial temperature to 100°C: This requires energy to raise the temperature.
2. Converting the water at 100°C to steam: This requires energy to change the state of matter from liquid to gas.
Constants for Water:
* Specific Heat Capacity of Water (c): 4.184 J/(g°C)
* Heat of Vaporization of Water (ΔHvap): 2260 J/g
* Density of Water: 1 g/mL
Calculations
1. Calculate the mass of water:
* 100 mL * 1 g/mL = 100 g
2. Assume an initial temperature of 20°C (room temperature):
3. Calculate the energy to raise the temperature:
* Energy = mass * specific heat capacity * change in temperature
* Energy = 100 g * 4.184 J/(g°C) * (100°C - 20°C)
* Energy = 33,472 J
4. Calculate the energy to vaporize the water:
* Energy = mass * heat of vaporization
* Energy = 100 g * 2260 J/g
* Energy = 226,000 J
5. Total energy required:
* Total energy = energy for heating + energy for vaporization
* Total energy = 33,472 J + 226,000 J
* Total energy = 259,472 J
Answer:
It takes approximately 259,472 Joules (J) of energy to boil 100 mL of water, assuming an initial temperature of 20°C.
