Which would burn the most 100 g of water at 100 degrees C or 100 g of steam at 100 degrees C?
The steam gives out more heat in cooling to body temperature because it has to give off the heat of the phase change from steam to water (heat of vaporization) as well as the heat required for the temperature change from 100 C to body temp.
To determine which would burn more, 100 g of water at 100 degrees Celsius or 100 g of steam at 100 degrees Celsius, we need to consider the concept of specific heat capacity.
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by a certain amount. The specific heat capacity of water is 4.186 J/g°C (joules per gram per degree Celsius). This means that it takes 4.186 joules of energy to raise the temperature of 1 gram of water by 1 degree Celsius.
Now, let's compare the two scenarios:
1. 100 g of water at 100 degrees Celsius:
Since the initial temperature is already 100 degrees Celsius, no additional heat energy is needed to raise the temperature. The only heat energy required would be the energy needed to vaporize the water, which is known as the heat of vaporization. The heat of vaporization for water is approximately 40.7 kJ/g. So, to completely vaporize 100 grams of water at 100 degrees Celsius, you would need:
40.7 kJ/g x 100 g = 4.07 MJ (mega-joules) of energy.
2. 100 g of steam at 100 degrees Celsius:
Steam is already in the gaseous form, so no additional energy is needed to vaporize it. However, steam at 100 degrees Celsius still has a significant amount of heat energy. To find out the total amount of energy, we need to calculate the sensible heat, which is the heat energy required to raise the temperature from 100 degrees Celsius to the boiling point (100 degrees Celsius). Since the specific heat capacity of steam is 2.03 J/g°C, we can calculate:
2.03 J/g°C x 100 g x (100°C - 100°C) = 0 J (no energy required)
Comparing the two scenarios, we can see that burning 100 g of water at 100 degrees Celsius would require more energy (4.07 MJ) compared to burning 100 g of steam at 100 degrees Celsius (0 J).
Therefore, burning 100 g of water at 100 degrees Celsius would release more energy than burning 100 g of steam at 100 degrees Celsius.