Liquid nitrogen is routinely used as a cryogenic coolant
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
Liquid nitrogen is routinely used as a cryogenic coolant. At 77 K and 1 atm its density is 0.808 g cm⁻³. Gaseous nitrogen behaves nearly ideally at 298 K and 1 atm.
Molar mass of N₂ = 28.02 g mol⁻¹.
(a) Calculate the molar volume of liquid N₂ at 77 K.
(b) Calculate the molar volume of N₂(g) at 298 K and 1 atm, treating the gas as ideal.
(c) Determine the factor by which the molar volume changes when nitrogen is vaporized under the stated conditions. Show your calculation.
(d) Explain, in terms of molecular spacing and intermolecular forces, why the factor you obtained in part (c) is so much larger than the factor you would obtain when comparing the solid and liquid states of a typical molecular substance.