Why is Ke different for lighter vs heavier molecules at the same temperature?
At a given temperature, different gasses will still have the same average kinetic energy per molecule. Since basic physics tells us that KE=1/2 m (v^2), we know v=sqrt(2KE/m). This means lighter molecules will have a larger average velocity than heavy molecules at the same temperature.
Do molecules with high kinetic energy evaporate?
This is because the molecules with the highest kinetic energy are lost to evaporation (see the video on evaporative cooling for more info). In humans and other organisms, the evaporation of sweat, which is about 99\% water, cools the body to maintain a steady temperature.
Do any water molecules become gas particles when the vapor pressure is lower than atmospheric pressure Why or why not?
The line on the graph shows the boiling temperature for water. As the temperature of a liquid or solid increases its vapor pressure also increases. Conversely, vapor pressure decreases as the temperature decreases….
| substance | vapor pressure at 25oC |
|---|---|
| water | 0.03 atm |
Do all molecules have the same kinetic energy at a given temperature?
Not all of the particles of a substance have the same kinetic energy. At any given time, the kinetic energy of the particles can be represented by a distribution. Some atoms or molecules have a lot of kinetic energy and move very fast. Other atoms or molecules have a little kinetic energy and move very slowly.
Why do light and heavy particles have the same kinetic energy?
The average kinetic energy of the light particles equals the average kinetic energy of the heavy particles – this can only happen if the average speed of the heavy particles is smaller than that of the light particles.
Why does temperature decrease during evaporation?
In order for a liquid molecule to escape into the gas state, the molecule must have enough kinetic energy to overcome the intermolecular attractive forces in the liquid. As a result, the liquid molecules that remain now have lower kinetic energy. As evaporation occurs, the temperature of the remaining liquid decreases.
What happens to the kinetic energy and temperature of molecules which did not escape and were left in the liquid state?
Usually, the molecules in a glass of water do not have enough heat energy to escape from the liquid. With sufficient heat, however, the liquid would quickly turn into vapor. As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid decreases.
What happens when pressure is greater than vapor pressure?
When that happens, it enables bubbles of vapor to form throughout the liquid – those are the bubbles you see when a liquid boils. If the external pressure is higher than the saturated vapor pressure, these bubbles are prevented from forming, and you just get evaporation at the surface of the liquid.
How did the water molecules become gas?
Evaporation happens when a liquid substance becomes a gas. When water is heated, it evaporates. The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapor. Water is evaporating, but staying in the air as a vapor.
Does kinetic energy equal temperature?
Temperature. Temperature is directly proportional to the average translational kinetic energy of molecules in an ideal gas.
Does same average kinetic energy mean same temperature?
The average kinetic energy of gas particles is dependent on the temperature of the gas. Temperature remains the same, so the average kinetic energy and the rms speed should remain the same.
Do heavier molecules have higher kinetic energy?
Temperature is directly proportional to the average kinetic energy of gas molecules. Lighter gases will have higher velocities than heavier gases, at the same temperature and pressure. In the Kelvin scale, 0K means the particles have no kinetic energy.
What happens to the speed of molecules as temperature decreases?
If temperature decreases, KE avg decreases, more molecules have lower speeds and fewer molecules have higher speeds, and the distribution shifts toward lower speeds overall, that is, to the left. This behavior is illustrated for nitrogen gas in Figure 3.
How does temperature affect the kinetic energy of a gas?
If the temperature is increased, the average speed and kinetic energy of the gas molecules increase. If the volume is held constant, the increased speed of the gas molecules results in more frequent and more forceful collisions with the walls of the container, therefore increasing the pressure ([link]).
What happens to Amontons law when temperature increases?
Amontons’s law. If the temperature is increased, the average speed and kinetic energy of the gas molecules increase. If the volume is held constant, the increased speed of the gas molecules results in more frequent and more forceful collisions with the walls of the container, therefore increasing the pressure ( Figure 9.31 ).