The heat of vaporization AH, of methanol (CH,OH) is 35.3 kJ/mol. Calculate the change in entropy AS when 5.0 g of methanol condenses at 65.0 °C. Be sure your answer contains a unit symbol and the correct number of significant digits.

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Chapter1: Chemical Foundations
Section: Chapter Questions
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#2 Solve the problem, please read directions carefully.  Thumbs up if you do it correctly. Be sure to round your answer to 2 decimal units. Please see the example I provided in the screenshot.

The answer should be in this type of format with this unit symbol -- (example: -0.0057 kJ/K)

3.4 g
kJ
5.6
mol
The moles of ammonia (in the second parentheses) are equal to the mass of
ammonia divided by the molar mass of ammonia.
17.0305 g·mol
1.118... kJ
There are 2 significant digits in this calculated value, but keep 2 extra digits for
now.
Now you must stop and think carefully about the sign of Q. Use the fact that heat is defined to be positive if the energy of the system
increases, and negative if the energy of the system decreases.
In this case, energy must flow out of the system for the NH,
to freeze, so Q must be negative:
Q=-1.118 kJ
You're next step is to divide Q by the temperature. Be careful! You need to use the absolute temperature, in kelvins:
There is 1 significant decimal place in this calculated value, but keep all of the
T=(-78.0+273.15) K= 195.15 K
decimal places for now.
Now you're ready to use the Clausius equation:
-1.118 kJ
kJ
=-0.005729...
K
AS=
195.15 K
Since there were 2 significant digits in your calculated value for Q and 4 significant digits in the absolute temperature, you should
round your final answer to 2 significant digits.
Transcribed Image Text:3.4 g kJ 5.6 mol The moles of ammonia (in the second parentheses) are equal to the mass of ammonia divided by the molar mass of ammonia. 17.0305 g·mol 1.118... kJ There are 2 significant digits in this calculated value, but keep 2 extra digits for now. Now you must stop and think carefully about the sign of Q. Use the fact that heat is defined to be positive if the energy of the system increases, and negative if the energy of the system decreases. In this case, energy must flow out of the system for the NH, to freeze, so Q must be negative: Q=-1.118 kJ You're next step is to divide Q by the temperature. Be careful! You need to use the absolute temperature, in kelvins: There is 1 significant decimal place in this calculated value, but keep all of the T=(-78.0+273.15) K= 195.15 K decimal places for now. Now you're ready to use the Clausius equation: -1.118 kJ kJ =-0.005729... K AS= 195.15 K Since there were 2 significant digits in your calculated value for Q and 4 significant digits in the absolute temperature, you should round your final answer to 2 significant digits.
The heat of vaporization AH, of methanol (CH,OH) is 35.3 kJ/mol. Calculate the change in entropy AS when 5.0 g of methanol condenses at 65.0 °C.
Be sure your answer contains a unit symbol and the correct number of significant digits.
x10
?
미□
Transcribed Image Text:The heat of vaporization AH, of methanol (CH,OH) is 35.3 kJ/mol. Calculate the change in entropy AS when 5.0 g of methanol condenses at 65.0 °C. Be sure your answer contains a unit symbol and the correct number of significant digits. x10 ? 미□
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