A sample of gaseous HCl is examined at two temperatures
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
A sample of gaseous HCl is examined at two temperatures, 200K and 800K, at constant density. Which statement describes how the relative importance of dipole–dipole interactions compared with London dispersion forces changes as the temperature increases from 200K to 800K?
(a) Both interactions increase equally with temperature, so their relative importance is unchanged.
(b) London dispersion forces become negligible at 800K because the thermal motion prevents formation of instantaneous dipoles.
(c) Dipole–dipole interactions become relatively less important because rapid molecular rotation at 800K averages the orientation of dipoles, whereas London dispersion forces are unaffected by rotation.
(d) Dipole–dipole interactions become relatively more important because higher kinetic energy helps the dipoles align during collisions, while London dispersion forces remain constant.