Heat needed to change temperature of hydrogen gas

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SUMMARY

The discussion focuses on calculating the heat required to change the temperature of 0.650 moles of hydrogen gas from 50 K to 100 K using the formula Q=nC_v(T_f-T_i). The user initially misapplied the specific heat capacity for diatomic hydrogen, incorrectly calculating C_v as 20.775 J/mol·K. The correct approach involves using the appropriate C_v value for diatomic hydrogen, which is 5/2 R, and ensuring the correct mass is used in calculations. Ultimately, the user struggled to arrive at the correct heat value, indicating a misunderstanding of the application of the ideal gas law and specific heat capacities.

PREREQUISITES
  • Understanding of the ideal gas law
  • Knowledge of specific heat capacities for diatomic gases
  • Familiarity with the concept of moles in chemistry
  • Basic proficiency in thermodynamic equations
NEXT STEPS
  • Review the calculation of heat transfer using Q=nC_v(T_f-T_i) for diatomic gases
  • Study the differences between monatomic and diatomic gas properties
  • Learn about the ideal gas law and its applications in thermodynamics
  • Explore the significance of the specific heat capacity constant R in gas calculations
USEFUL FOR

Chemistry students, thermodynamics enthusiasts, and anyone involved in gas law calculations will benefit from this discussion.

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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