HW Question 8.9

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HW Question 8.9

Postby Abigail_Low_1A » Sun Jan 15, 2017 8:13 pm

8.9 An ideal gas in a cylinder was placed in a heater and gained 5.50kJ of energy as heat. If the cylinder increased in volume from 345 mL to 1846 mL against an atmospheric pressure of 750 Torr during the process, what is the change in internal energy of the gas in the cylinder?

The solution manual uses ideal gas constants to convert to joules, how come we can't use 1L*atm = 101.325 J for the conversion, knowing 1 atm = 760 Torr?

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Re: HW Question 8.9

Postby Chem_Mod » Sun Jan 15, 2017 8:16 pm

If it gives you the same answer it doesn't matter.

Riley Seid 1L
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Re: HW Question 8.9

Postby Riley Seid 1L » Mon Jan 16, 2017 6:01 pm

Will all of these conversion factors/constants be given on an exam or quiz?

Julia Nakamura 2D
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Re: HW Question 8.9

Postby Julia Nakamura 2D » Mon Jan 16, 2017 6:48 pm

Yes, the constants and formulas on page 125 of the course reader are all given on quizzes and exams.

mhuang 1E
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Re: HW Question 8.9

Postby mhuang 1E » Mon Jan 15, 2018 11:44 pm

To add on, could someone expand what is the ideal gas constant?

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Re: HW Question 8.9

Postby soniatripathy » Tue Jan 16, 2018 1:29 am

The following are the gas constants given on the equations and constants sheet:
R = 8.314 J·K-1·mol-1 = 8.206 × 10-2 L·atm·K-1·mol-1 =8.314 x 10-2 L·bar·K-1·mol-1 = 62.364 L·Torr·K-1·mol-1

This is the energy per temperature increment per mole. It is very important to note the units when using this in calculations because otherwise the answer will be messed up. Usually pick the one that works best with the units already given in the problem.

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