Heat needed to change temperature of hydrogen gas

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Homework Help Overview

The discussion revolves around calculating the heat required to change the temperature of hydrogen gas in a rigid container from 50 K to 100 K. The participants are exploring the appropriate equations and constants to use for this thermodynamic problem.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to use the equation Q=nC_v(T_f-T_i) but expresses confusion over the results obtained for both diatomic and monatomic hydrogen. Participants question the correctness of the specific heat capacity used and the mass calculations.

Discussion Status

Participants are actively engaging with the problem, raising questions about the assumptions made regarding the type of hydrogen gas and the calculations performed. There is a recognition of potential contradictions in the results, and some guidance is being offered regarding the mass and specific heat capacity considerations.

Contextual Notes

There is mention of the molar mass of hydrogen gas and the distinction between diatomic and monatomic forms, which may affect the calculations. The participants are also grappling with the implications of using the correct values in their equations.

Kalie
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A rigid container holds 0.650 of hydrogen gas. How much heat is needed to change the temperature of the gas from 50 K to 100 K?
All right I know this is easy but for some reason I can't get the right answer what i have been doing is using the equation Q=nC_v(T_f-T_i)
Hydrogen gas is 1 g/mol
so n= .65 mol
C_v= 5/2 R= 20.775
because hydrogen gas is diatomic?
(T_f-T_i)= 100-50= 50
so putting it all together I get 675.188
which is wrong I made Hydrogen monotomic for the hay of it and got 405 J which is wrong too.
Please tell me what I am doing wrong...:cry:
 
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Kalie said:
A rigid container holds 0.650 of hydrogen gas. How much heat is needed to change the temperature of the gas from 50 K to 100 K?
All right I know this is easy but for some reason I can't get the right answer what i have been doing is using the equation Q=nC_v(T_f-T_i)
Hydrogen gas is 1 g/mol
so n= .65 mol
C_v= 5/2 R= 20.775
because hydrogen gas is diatomic?
(T_f-T_i)= 100-50= 50
so putting it all together I get 675.188
which is wrong I made Hydrogen monotomic for the hay of it and got 405 J which is wrong too.
Please tell me what I am doing wrong...:cry:

See the highlights in the quote. A contradiction?
 
OlderDan said:
See the highlights in the quote. A contradiction?
But i also calculated it for monotomic too...
 
Kalie said:
But i also calculated it for monotomic too...

Did you calculate it for diatomic using the correct mass?
 
OlderDan said:
Did you calculate it for diatomic using the correct mass?
Oh!
But When I do that I get
.65/2 = .325
.325*20.775*50 = 337.6 which is still wrong
 
nevermind monatomic at that temp
 

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