A sample of neon (Ne) gas has a pressure of 277KPa at 56 o . Calculate the density of the gas.

Question

A sample of neon (Ne) gas has a pressure

of 277KPa at 56 o . Calculate the density of

the gas.

Answer 1

Density = mass / volume

Let us assume we have 1 liter of gas. We can then use the ideal gas law to find the number of moles, then convert that to mass and thus obtain the density.

PV = nRT

P = pressure in atm = 277 kPa x 1 atm / 101.325 kPa = 2.73 atm

V = volume in L = 1 L

n = moles = ?

R = gas constant = 0.0821 Latm/Kmol

T = temperature in Kelvin = 56ºC + 273 = 329K

Solving for n, we have...

n = PV/RT = (2.73)(1) / (0.0821)(329)

n = 0.101 moles of Ne

Atomic mass of Ne = 20.2 g/mol

Mass of Ne present = 0.101 mols x 20.2 g/mol = 2.04 g

Density = mass / volume = 2.04 g/L