# The particles which of the following gases has the highest/lowest average speed? Which gas particles have the highest/lowest average kinetic energy? a.) argon at 20°C. b.)nitrogen at 20°C b.) nitrogen at 100°C. c.) helium at 100°C

Mar 11, 2018

Highest speed: Helium at 100°C.
Lowest speed: Argon at 20°C.

Highest kinetic energy: Nitrogen and helium at 100°C.
Lowest kinetic energy: Nitrogen and argon at 20°C.

#### Explanation:

Temperature is a measure of average kinetic energy.

Therefore, at the same temperature, gases have the same average kinetic energy.
But different gas particles move at different speeds with this kinetic energy—gases with smaller particles tend to be moving faster at the same temperature, which means they have a higher speed.

At variable temperatures, gases with both smaller particles and higher temperatures will have a higher speed.

Here are our choices:

1. Argon at 20°C.
2. Nitrogen at 20°C.
3. Nitrogen at 100°C.
4. Helium at 100°C.

Helium has both the smallest particles and is at the high temperature of 100°C , so it will be the gas with the highest speed.
Argon has the biggest particles and is at the low temperature of 20°C, so it will be the gas with the highest speed.

Particles at the same temperature have the same average kinetic energy, so argon and nitrogen, which are at 20°C, are the gases with the lowest average kinetic energy.
Nitrogen and helium, at 100°C, have the highest average kinetic energy because they have the highest temperature.