Please Help!!
Using heat of fusion, Specific heat, or heat of evaporation.
Calories to condense 135g of steam at 100 degrees C and to cool the liquid to 15 degrees C.
This is how I calculated it using heat of evaporation:
135gx540 cal=72900cal
72900cal/135g x (delta T)85 degrees C= 6.4
I know the correct answer is 8.44 x 10^4
So what did I do wrong?
Thank you!
35gx540 cal=72900cal
This first step is right. 72.9 kcal to condense 135 g steam at 100 C to liquid at 100 C. The error is the next step.
The next step is heat removed to cool liquid water at 100 to 15 C is
135g x 1 cal/g*C x (15-100) = ?
Then add step 1 to step 2 for total heat released.
72900cal/135g x (delta T)85 degrees C= 6.4
I know the correct answer is 8.44 x 10^4
To find the total calories required to condense the steam and cool the liquid, you need to consider two steps: condensing the steam and cooling the liquid.
1. Condensing the steam:
The heat of evaporation is the amount of heat required to convert 1 gram of a substance from liquid to vapor at its boiling point. In this case, we need to calculate the calories required to condense the steam at 100 degrees Celsius.
To calculate this, you need to use the formula:
Q = m x ΔHvap
Where:
Q = heat energy (calories)
m = mass (135g)
ΔHvap = heat of evaporation (given or known)
You did this step correctly:
Q = 135g * 540 cal/g = 72900 cal
2. Cooling the liquid:
After condensing the steam, you need to calculate the calories required to cool the liquid from 100 degrees Celsius to 15 degrees Celsius. For this step, you need to use the specific heat formula:
Q = m x c x ΔT
Where:
Q = heat energy (calories)
m = mass of the liquid (135g)
c = specific heat (given or known)
ΔT = change in temperature (100 - 15 = 85 degrees Celsius)
Here's where you made a mistake in your calculation:
Q = 135g * c * ΔT = 135g * c * 85 degrees Celsius
Since you're not given the specific heat value, you cannot calculate the correct value without it.
To get the correct answer of 8.44 x 10^4 calories, you need to know the specific heat value and substitute it into the formula.
So, without the specific heat value, it is not possible to determine the total calories needed to condense the steam and cool the liquid.