A patient arrives in the emergency room with a burn caused by steam. Calculate the heat that is released when 10.7 g of steam at 100. ∘C hits the skin, condenses, and cools to body temperature of 37.0 ∘C. (For water, 540 cal (2260 J) is needed to convert 1 g of water to vapor at 100 ∘C.)
Express the heat to three significant figures and include the appropriate units.
q1 = heat released when steam @ 100 C condenses to liquid water.
q1 = 10.7 g x 2260 J/g = ?
q2 = heat released when water @ 100 C is cooled to 37 C.
q2 = 10.7 g x 4.18 J/g*c x (Tfinal-Tinitial) = ? J where Ti is 100 and Tf is 100 C.
Total q is q1 + q2
Post your work if you get stuck.
@DrBob222..
I still need help with that. I need help solving it by step by step
Hint: Try to recall that condensation is the route by which water vapor in the air is changed into liquid water. … It is known to you that for any substance, the condensation point is the same as the boiling point and the boiling point of water is 100 degree Celsius.
To calculate the heat released when the steam hits the skin and condenses, we need to consider two steps: first, the heat released as the steam condenses, and second, the heat released as the condensed water cools to body temperature.
Step 1: Heat released during condensation
We are given that 540 cal (2260 J) is needed to convert 1 g of water to vapor at 100 ∘C. Since we have 10.7 g of steam, we can determine the heat released during condensation using a proportion:
(10.7 g of steam) / (1 g of water) = X / (540 cal) [where X is the heat released]
Rearranging the equation, we have:
X = (10.7 g of steam) * (540 cal) / (1 g of water)
Calculating the value of X, we have:
X = 577.8 cal (rounded to three significant figures)
Step 2: Heat released during cooling to body temperature
To find the heat released as the condensed water cools to body temperature, we need to consider the specific heat capacity of water. The specific heat capacity of water is 1 cal/g⋅∘C (4.184 J/g⋅∘C).
Using this information, we can calculate the heat released as the water cools from 100 ∘C to 37.0 ∘C. The equation to calculate this is:
Heat = mass * specific heat capacity * change in temperature
Heat = (10.7 g) * (1 cal/g⋅∘C) * (100 ∘C - 37.0 ∘C)
Calculating the value of heat, we have:
Heat = 698.1 cal (rounded to three significant figures)
Therefore, the total heat released when 10.7 g of steam at 100 ∘C hits the skin, condenses, and cools to body temperature is approximately 577.8 cal + 698.1 cal = 1275.9 cal.
Expressed in the appropriate units and rounded to three significant figures, the heat released is approximately 1276 cal.
q1 = 10.7 g x 2260 J/g = ?
q2 = 10.7 g x 4.18 J/g*c x (Tfinal-Tinitial) = ? J where Ti is 100 and Tf is 100 C.
You still need help? Are you telling me that you can't multiply 10.7 x 2200 and come up with q1.
I made a typo on q2. It should be Tf = 37 and Ti = 100
Are you saying you cant solve q2 = 10.7 x 4.18 x (37 - 100)