Finding temperature change, thermodynamics first law

In summary, the conversation involved calculations using the PV=nRT equation to determine the final and initial pressures and temperatures. The final pressure was found to be 96629 and the initial pressure was 62639. However, there was a discrepancy with the temperatures, with an initial temperature of 81.79 and a final temperature of 167.747, resulting in a change of 85.957. The expert does not confirm the calculated pressures and questions the presence of a 1.5 factor in the ideal gas temperature calculation.
  • #1
JoeyBob
256
29
Homework Statement
see attached
Relevant Equations
PV=nRT
So I calculated the final and initial pressures using the given eqns, ended up with the final pressure of 96629 and initial pressure of 62639.

Then I used the PV=nRT eqn to calculate the final and initial temperatures. T=P*V/(n*1.5*R).

I got an initial temperature of 81.79 and a final temperature of 167.747, which is a change in temperature of 85.957 but the answer is 122.74.
 
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  • #2
JoeyBob said:
Homework Statement:: see attached
Relevant Equations:: PV=nRT

So I calculated the final and initial pressures using the given eqns, ended up with the final pressure of 96629 and initial pressure of 62639.

Then I used the PV=nRT eqn to calculate the final and initial temperatures. T=P*V/(n*1.5*R).

I got an initial temperature of 81.79 and a final temperature of 167.747, which is a change in temperature of 85.957 but the answer is 122.74.
So, is there a problem statement somewhere involved here?
 
  • #3
Also, attaching units to your numbers would be helpful.
 
  • #4
Chestermiller said:
So, is there a problem statement somewhere involved here?

My bad. its attached to this reply
 

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  • #5
Your pressures are way off. Please redo the calculation.
 
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Likes JoeyBob
  • #6
I don't confirm either of the pressures you calculated. Also, what is that 1.5 factor doing in the denominator of your ideal gas temperature calculation?
 

FAQ: Finding temperature change, thermodynamics first law

What is the first law of thermodynamics?

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or converted from one form to another.

How is temperature change related to the first law of thermodynamics?

Temperature change is a result of energy transfer, which is governed by the first law of thermodynamics. When energy is transferred into or out of a system, it can cause a change in temperature.

How do you calculate temperature change using the first law of thermodynamics?

To calculate temperature change, you would need to know the amount of energy transferred into or out of a system, as well as the specific heat capacity of the material. By using the equation Q = mcΔT, where Q is the energy transferred, m is the mass of the material, c is the specific heat capacity, and ΔT is the change in temperature, you can calculate the temperature change.

What is an example of the first law of thermodynamics in action?

An example of the first law of thermodynamics is a hot cup of coffee cooling down. As the coffee transfers heat to its surroundings, it loses energy and its temperature decreases. This is in accordance with the first law of thermodynamics, as the energy is not lost but rather transferred to the surroundings.

How does the first law of thermodynamics relate to the concept of energy conservation?

The first law of thermodynamics is essentially a statement of energy conservation, as it states that energy cannot be created or destroyed. This means that the total amount of energy in a closed system will remain constant, and any changes in energy are due to energy transfer or conversion.

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