# What is the density of uranium hexafluoride gas at 60 C and .98 atm in g/mL?

Density is mass divided by volume.  Uranium hexafluoride, UF6, has a molar mass of 352.0 grams per mole. We can use the ideal gas law which relates volume, temperature, pressure and number of moles of gas to solve this. We don't have a specific volume or number of moles, but...

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Density is mass divided by volume.  Uranium hexafluoride, UF6, has a molar mass of 352.0 grams per mole. We can use the ideal gas law which relates volume, temperature, pressure and number of moles of gas to solve this. We don't have a specific volume or number of moles, but we can make some substitutions in the ideal gas law to arrive at an equation used to find the density of a gas if the pressure, temperature and molar mass are known. The temperature must be converted to Kelvins: 60ºC +272=333K

PV = nRT

V = nRT/P

Molar mass = mass/moles, so mass = (M)(n).

Density = m/V

d = Mn/V

V = Mn/d

Rearrange PV=nRT: PV/n = RT

Substitute Mn/d for V: PMn/dn = RT

Cancel out "n" and rearrange:

d = PM/RT

We now have an equation that will give us density if we know pressure, molar pass of the gas, and temperature:

d =  (0.98 atm)(352.0 g/mol)/(0.0821 L-atom/mol-K)(333 K) = 12.61 gram/L

Convert to grams/mL:

12.61 grams/L x 1 L/1000 ml = 0.0126 g/ml

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