Question

Rank the following gases in order of increasing root-mean-square velocity at 50ºC: HCl, CO2, Br2, PF5, Ne

Answer 1

To rank the gases HCl, CO2, Br2, PF5, and Ne by increasing root-mean-square velocity at 50ºC, one needs to consider their molar masses. Since the temperature is constant, the ranking is from lightest to heaviest molar mass. Hence, the order is Ne, HCl, CO2, PF5, Br2.

Step-by-step explanation:

The question asks to rank the following gases in order of increasing root-mean-square velocity at 50ºC: HCl, CO2, Br2, PF5, Ne. The root-mean-square velocity is dependent on both the temperature and the molar mass of a gas. Considering the question is set at a constant temperature, the ranking will solely depend on the molar mass of the gases.

Molecules with lesser molar mass will have higher velocities. Therefore, the gas with the lowest molar mass will have the highest root-mean-square velocity, and vice versa.

By looking up the molar masses:

• Ne = 20.18 g/mol
• HCl = 36.46 g/mol
• CO2 = 44.01 g/mol
• PF5 = 125.96 g/mol
• Br2 = 159.808 g/mol

Ranking these from the smallest to largest molar mass gives us the order:

1. Ne
2. HCl
3. CO2
4. PF5
5. Br2

This means that at 50ºC, the increasing order of root-mean-square velocities for the gases listed is Ne, HCl, CO2, PF5, Br2.