What is the density at STP of the gas sulfur hexafluoride, SF_6?

1 Answer
May 1, 2016

The density of "SF"_6 at STP is 6.43 g/L.

Explanation:

We can use the Ideal Gas Law to solve this problem.

color(blue)(|bar(ul(color(white)(a/a)PV = nRT color(white)(a/a)|)))" "

Since "moles" = "mass"/"molar mass" or n = m/M, we can write

PV = m/MRT

We can rearrange this to

PM = m/VRT

But "density"= "mass"/"volume" or color(brown)(|bar(ul(color(white)(a/a)ρ = m/Vcolor(white)(a/a)|)))" "

PM = ρRT and

color(blue)(|bar(ul(color(white)(a/a)ρ = (PM)/(RT)color(white)(a/a)|)))" "

STP = 1 bar and 0 °C, and the molar mass of "SF"_6 is 146.06 g/mol.

ρ = (1 color(red)(cancel(color(black)("bar"))) × "146.06 g"·color(red)(cancel(color(black)("mol"^"-1"))))/("0.083 14" color(red)(cancel(color(black)("bar")))·"L"·color(red)(cancel(color(black)("K"^"-1""mol"^"-1"))) × 273.15 color(red)(cancel(color(black)("K")))) = "6.43 g/L"