# The proportion of Hydrogen to limit errors in measurement.

1. May 14, 2013

### rrab186

It is proposed to use a katharometer to mesaure the amount (about 5%) of oxygen in nitrogen, in the presence of a small amount (0.5%) hydrogen. How constant would the proportion of hydrogen have to be in order to limit errors in measurement of % oxygen to +/- 0.1%?

The thermal conductivities are:
Nitrogen 0.993
Oxygen 1.052
Hydrogen 6.993

Not to sure where to start with this one, any guidance just to start me off would be most appreciated.

2. May 15, 2013

### chemisttree

An approximation of the mixture's thermal conductivity can be expressed as the mole fraction-weighted sum of the individual components. For example,

λm = χ1λ1 + χ2λ2 +… χnλn