# Homework Help: Thermodynamics Questions for Helium and Flourine

1. Jul 7, 2008

### Tofuphysics

Hey all, I just discrovered these forums, thankoodness, because I'm taking physics over the summer (its a requirement at my school), and not being a science-y person, I really need help.

1. The problem statement, all variables and given/known data

This is the problem:

Problem 1
a. What is the average translational kinetic energy of a helium atom at 300 K?
b. What is the average translational velocity of a helium atom at 300 K?
c. What is the total internal energy of a 4.0 g sample of He at 300 K?
d. What is the total internal energy of a 4.0 g sample of He at 301 K?
e. How much energy is needed to raise the temperature of 4.0 g of He by one degree K?

And then the next problem is he same cocept, but with Flourine (F2)

Problem 2
a. What is the average translational kinetic energy of a F2 molceule at 300 K?
b. What is the average translational velocity of a F2 moelcule at 300 K?
c. What is the total internal energy of a 38 g sample of F2 at 300 K?
d. What is the total internal energy of a 38 g sample of F2 at 301 K?
e. How much energy is needed to raise the temperature of 38 g of F2 by one degree K?

2. Relevant equations
KE=(3/2)(Kb)(T)
KE=1/2mv^2
1 MW= 1x wx^6 w (i dont know what this means but the teacher wrote it on the board)

3. The attempt at a solution
I think that you have to use the KE equations and the molar mass (which you can figure out using the periodic table?) but I'm really not sure how to put it together.

Thankyou so much if you had the patience to read all that!
-Tofuphysics

Last edited: Jul 7, 2008
2. Jul 7, 2008

### Hootenanny

Staff Emeritus
Welcome to PF Tofuphysics,
Assuming of course that you are treating these gases as ideal, then those equations are correct and will certainly allow you to answer questions (a) and (b) in each case. However, a third equation would be infinitely more useful in answering the remaining parts.