# Gas in a gallon of hydrogen

1. Feb 19, 2013

### GTeclips

Hello.

I'm just wondering how many cubic feet of gaseous hydrogen are in one gallon of liquid hydrogen. I know I'm not being too specific and that many variables are involved (temperature, atmospheric pressure... etc), but approximately how many are in a gallon? And yes, I have checked Google. I have found nothing useful.

I wish to perform small scale experiments with hydrogen as a lifting gas in small balloons, in case you're curious.

Sorry for not using metric, I'm used to U.S.

Thank you!

2. Feb 19, 2013

### Ygggdrasil

Well, the density of liquid hydrogen is 67.80 kg/m³. From this value, you can find the number of moles of hydrogen in a gallon of liquid hydrogen, and from that number you can calculate the volume of gaseous hydrogen at your specified temperature and pressure.

3. Feb 20, 2013

### chemisttree

Without being too precise, there about 4L per gallon. Each mole of hydrogen (2g) should produce about 23 L of gas or 5.5 gal. You will need to determine the volume in cubic feet per gallon.