A hot steam burn is worse than boiling water burn:
(a) If 4 mL of 100°C hot steam condenses on your arm, how much energy is released as it condenses and cools to human body temperature of 37°C?
(b) If 4 mL of 100°C hot water spills on your arm, how much energy is released as it cools to human body temperature of 37°C?
To answer these questions, we can use the specific heat capacity and latent heat of vaporization of water.
(a) To calculate the energy released when 4 mL of hot steam condenses, we need to find the amount of heat energy transferred during the condensation process.
The specific heat capacity of water is 4.18 J/g°C, and the latent heat of vaporization of water is 2260 J/g.
First, we need to find the mass of 4 mL of water. The density of water is 1 g/mL, so 4 mL of water corresponds to a mass of 4 grams.
The energy released during the phase change from steam to water is given by the formula:
Energy released = Mass of water * Latent heat of vaporization
= 4 g * 2260 J/g
= 9040 J
Next, we need to calculate the energy released as the water cools from 100°C to 37°C. We can use the formula:
Energy released = Mass of water * Specific heat capacity * Change in temperature
The change in temperature is 100°C - 37°C = 63°C.
Energy released = 4 g * 4.18 J/g°C * 63°C
= 1051.68 J
The total energy released is the sum of the energy released during condensation and the energy released during cooling:
Total energy released = Energy released during condensation + Energy released during cooling
= 9040 J + 1051.68 J
= 10091.68 J
Therefore, approximately 10,091.68 J of energy is released when 4 mL of hot steam condenses and cools to human body temperature.
(b) Similarly, let's calculate the energy released when 4 mL of hot water spills and cools.
Using the same formulas and values as above, we have:
Energy released during phase change (from liquid to solid) = Mass of water * Latent heat of vaporization
= 4 g * 2260 J/g
= 9040 J
Energy released during cooling = Mass of water * Specific heat capacity * Change in temperature
= 4 g * 4.18 J/g°C * 63°C
= 1051.68 J
Total energy released = Energy released during phase change + Energy released during cooling
= 9040 J + 1051.68 J
= 10091.68 J
Therefore, approximately 10,091.68 J of energy is released when 4 mL of hot water spills and cools to human body temperature.
From these calculations, we can see that the amount of energy released in both cases is the same. The severity of a burn depends on several factors such as contact time, temperature, and the specific heat capacity of the material involved.
To answer these questions, we need to calculate the amount of energy released as the substances cool down.
(a) For hot steam burn:
To calculate the energy released when 4 mL of hot steam condenses and cools, we can use the formula:
Q = m * c * ΔT
Where:
Q = energy released (in joules)
m = mass of the substance (in grams)
c = specific heat capacity of the substance (in joules per gram-degree Celsius)
ΔT = change in temperature (in degrees Celsius)
In this case, the mass (m) of the steam is 4 grams (since 1 mL of water is approximately 1 gram). The specific heat capacity (c) of water is approximately 4.18 joules per gram-degree Celsius. The change in temperature (ΔT) is 100°C (initial temperature) minus 37°C (final temperature), which is 63°C.
So, plugging in the values, we have:
Q = 4 g * 4.18 J/g°C * 63°C
Q = 1051.68 J
Therefore, when 4 mL of hot steam condenses and cools to human body temperature, approximately 1051.68 joules of energy are released.
(b) For boiling water burn:
To calculate the energy released when 4 mL of hot water cools down, we can use the same formula as before:
Q = m * c * ΔT
In this case, the mass (m) of the water is 4 grams. The specific heat capacity (c) of water is the same, approximately 4.18 joules per gram-degree Celsius. The change in temperature (ΔT) is 100°C (initial temperature) minus 37°C (final temperature), which is 63°C.
So, plugging in the values, we have:
Q = 4 g * 4.18 J/g°C * 63°C
Q = 1051.68 J
Therefore, when 4 mL of hot water cools to human body temperature, approximately 1051.68 joules of energy are released.
From the calculations above, we can see that the amounts of energy released are the same for both hot steam and boiling water burns. However, it's worth noting that the severity of burns depends not only on the amount of energy released but also on other factors such as contact time, temperature, and heat transfer mechanisms.