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Q:
How do you measure the density of gas?
- Fiona (age 8)
Bronx, NY, USA
A:
Fiona -
There are two good ways of doing this. The first is that you can
take a certain amount of gas (in a balloon, for example) and weigh it
on a scale (if it's heavier than air) or measure how high it floats
(how 'bouyant' it is - if it's lighter than air). Then you can compare
how heavy/bouyant it is to the density of air to figure out how dense
the gas is.
The other way uses more math. The density of a gas is equal to the
gas's pressure divided by a constant number (R=0.08206 L*atm/K) and the
temperature (in degress Kelvin). (Or d = n/V = P/RT) So if you know the
temperature and the gas's pressure (the pressure of air is 1 atm), you
can figure out it's density.
-Tamara
(published on 10/22/2007)
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