Calculate the density of SO3 gas at STP.

Question

Hello! I'm having some difficulties grasping this chemistry concept. I'd love some help working this out. Thank you!

Answer 1

As a universal rule the molar volume of any gas at STP is 22.4 L (Conversion factor: 1 mol = 22.4 L)

Density = mass/volume

Molar mass (SO3) = atomic mass oxygen x 3 + atomic mass sulfur = 3(15.99 g/mol) + 32.06 g/mol = 80.066 g/mol SO3

Convert molar mass to density using the conversion factor above:

(80.066 g/mol) x (1 mol / 22.4 L) .... moles should cancel leaving you with g/L

= 3.57 g/L

In most literature you will find density in units of g/mL or g/cm³ so to convert from g/L to g/mL or g/cm³

Conversion factor: 1 L = 10³ mL = 10³ cm³

3.57 g/L x (1 L / 10³ mL) = 0.00357 g/mL = 0.00357 g/cm³

^{Hope this helps!}