Posted by **Bria** on Sunday, February 19, 2012 at 8:43pm.

You have two gas-filled balloons, one containing He and the other H2. The H2 balloon is twice the size of the He balloon (let the He balloon have a volume of 1 -L and the H2 balloon. a volume of 2 L). The pressure of gas in the H2 balloon is 1 atm while that in the He balloon is 2 atm. The H2 balloon is outside in the snow (-1.11oC) while the He balloon is inside a warm building (21.1oC).

a) Which balloon contains the greater number of molecules? Show calculation.

b) Which balloon contains the greater mass of gas? Show calculation.

- Chemistry -
**DrBob222**, Sunday, February 19, 2012 at 8:53pm
PV = nRT. Substitute and solve for n = number of moles. Convert to molecules remembering that 1 mol has 6.02E23 molecules.

b) n = grams/molar mass. You know n and molar mass. solve for grams and compare.

- Chemistry -
**Bria**, Sunday, February 19, 2012 at 9:03pm
Ok so for the first part I got x=0.08969 for H2 and x=0.082 for He. but how do I convert to molecules?

Working on the second part now

- Chemistry -
**Bria**, Sunday, February 19, 2012 at 9:10pm
ok so for the second part this is what I did.

0.082=x/4=0.328g

0.08969=x/2=0.179g

I feel like I have done something wrong though

- Chemistry -
**DrBob222**, Sunday, February 19, 2012 at 9:47pm
First part b. No, you didn't do anything wrong. I agree with the 0.179 for g H2 gas. I have 0.331 g for He probably because I used 0.0828 for moles. I think you rounded that or just didn't read the last digit from your calculator.

Also, on moles H2, I obtained 0.08959. I used 0.08206 for R and 273.15+(-1.11) for T.

For a part, remember that 1 mol of molecules has 6.02E23 molecules. Just convert with that factor.

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