# Constant Volume Gas thermometer

1. Oct 23, 2013

### LukeeVassallo

Hi,

Does it make a difference if you use nitrogen gas or oxygen gas or hydrogen gas in the bulb ? Or they all give the same readings given that an arbitrarily chosen constant if found for each ?

Many Thanks! :)

2. Oct 23, 2013

### LukeeVassallo

is found for each* - sry my bad

3. Oct 24, 2013

### Philip Wood

Suppose that P1 and P2 are the pressures of the gas in the bulb at two fixed point temperatures (e.g.pure melting ice and steam above water boiling at standard pressure. We find that the ratio P1/P2 does depend slightly on the gas in the bulb, but if we reduce the density of the gases, the ratio converges towards the same value whatever gas we use. We are approaching an 'ideal' gas (because the attractive forces between molecules, and the fraction of container space taken up by the molecules themselves are becoming negligible).