How to Calculate Heat Required to Double Internal Energy of Helium Gas?

In summary, a student is struggling with a physics problem involving the internal energy of a gas in a chamber with a frictionless piston. They are unsure of which equations to use and are seeking help on the forum. Another user suggests starting by finding the average kinetic energy of the gas molecules and then doubling the internal energy. The first student then figures out the solution by finding the new temperature and volume of the gas and using equations to find the work done and heat required. The original student thanks the forum for their help.
  • #1
boburd21
9
0
[SOLVED] Internal Energy Problem

Homework Statement



Given .15meters cubed of Helium gas at 300K and 3Pa in a chamber with a frictionless piston. How much heat is required to double the internal energy of the gas at constant pressure?

Homework Equations



I really don't know what equations to use, this problem is giving me a lot of trouble any help is greatly appreciated
 
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  • #2
You need to show some work to get help here. Those are the rules. You do not need to have calculations, but you must show that you have put some thought into the problem. I will give you some questions to consider to get you started:

1) The internal energy of a gas means the cummulative total of the kinetic energy of the gas molecules. Do you know a formula for the average kinetic energy of a molecule of a gas?

2) Once you know the kinetic energy of one of the Helium molecules, how can you use this to find the total average internal energy of the gas? HINT: The volume given will come into play here.
 
  • #3
Sorry, I am new to the forum but this take home test has driven me to look for help.
So far I found the moles of Helium originally in the Chamber using PV=nRT. I know i can use the Urms equation to find the average kinetic energy of a molecule and therefore the original amount of internal energy. My problem comes when Finding out how much of the heat added is turned into work compared to a temperature (internal energy) increase so that i can eventually use (delta)U= Q - W
 
  • #4
Istead of the Urms equation I am using Ke=3/2Rt to find average Ke per mole
 
  • #5
I guess all that I am asking is if there is an equation that shows how when Heat is added to an isobaric system how much of the heat goes into work and how much goes into temperature change. If anyone knows if there is such an equation or other ones i could use to figure it out that would be great.
 
  • #6
solved it on my own thanks for the start GO1
 
  • #7
boburd21 said:
Istead of the Urms equation I am using Ke=3/2Rt to find average Ke per mole

This is what I would use as well.

boburd21 said:
I guess all that I am asking is if there is an equation that shows how when Heat is added to an isobaric system how much of the heat goes into work and how much goes into temperature change. If anyone knows if there is such an equation or other ones i could use to figure it out that would be great.


Try starting off like this. Double the internal energy and find what the temperature of the gas would be. Then, knowing that the pressure must remain the same, you should be able to find the new volume of the gas.

Now, knowing the volume of the gas, can you find the work done by the gas?

If you know change in internal energy and the work done, can you find the heat that would need to be added.
 
  • #8
thats how i ended up solving it, thanks
 

1. What is the definition of internal energy?

Internal energy is the sum of all the energy within a system, including the kinetic energy of particles, potential energy due to the position of particles, and the energy associated with the bonds between particles.

2. How is internal energy different from heat and work?

Internal energy is a property of a system, while heat and work are forms of energy transfer. Heat is the transfer of energy due to a temperature difference, and work is the transfer of energy due to a force acting over a distance.

3. How can internal energy be changed?

Internal energy can be changed by adding or removing heat or work from a system. It can also change when the temperature, volume, or number of particles in a system changes.

4. What is the relationship between internal energy and temperature?

Internal energy is directly proportional to temperature, meaning that as the temperature of a system increases, so does its internal energy.

5. How is internal energy measured and expressed?

Internal energy is measured in joules (J) and is typically expressed as a change in internal energy (ΔU) rather than its absolute value.

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