Question

Calculate the density (at STP) of:
(i). hydrogen, H2

(ii). nitrogen, N2

(iii). butane, C4H10

Answer 1

Assuming that we have 1 mole of each gas at STP, we will use Molar mass and Molar volume to calculate density of each gas.

Molar Volume of any gas at STP is 22400mL

(i) Hydrogen, H₂

Molar mass=2.016g/mol

Molar volume=22400mL/mol

$Density=\dfrac{mass}{volume}=\dfrac{2.016g/mol}{22400mL/mol}$

= 9.0x10^-5g/mL

(ii) Nitrogen, N₂

Molar mass=28.0134g/mol

molar volume=22400mL

$Density=\dfrac{28.0134g/mol}{22400g/mol}=$ 1.25x10^-3g/mL

(iii) Butane, C₄H₁₀

Atomic mass=(C=12.0, H=1.008)

Molar mass= 4(12.0) + 10(1.008) = 58.08g/mol

Molar volume=22400mL

$Density=\dfrac{58.08g/mol}{22400mL/mol} =$ 2.59x10^-3g/mL