Gas Expansion: Exploring Effects of Temperature & Vacuum

[batballbat]

1. why does gas expand to fill a container when there is no increase in temperature or any force applied to it? ( I am confused with the rising effect of gas in air and the expanding effect. how can we distinguis it?)

2. how can we determine the limitation of gas expansion when there is no increase in
temperature?

3. will the gas expand in vacuum when there is no increase in temperature?

 

[Bloodthunder]

All of your questions can be answered with 1 word. Entropy.

A container with gas molecules packed together at one side and a vacuum at the other is of higher energy than one with even concentration throughout. Hence the air molecules will redistribute themselves to fill up the entire container. (This is one of the methods used to store energy.)

Rising effect of gas would be due to the density instead.

Not quite sure what you mean by: when there is no increase in temperature.

 

[batballbat]

when i searched this question in google, most of the answers i found were of the reason of expansion of gas due to heat supplied to it. So i was wondering why there is gas expansion even without the supply of heat.
i searched the term entropy in wikipedia but am struggling to understand it. Also i need the answer of my second question. i have found that gas expands only to a certain limit. But how can we determine it?

 

[Bloodthunder]

Well, gas can expand in a vacuum when there's a supply of heat. Otherwise, if in an enclosed container, just use the ol' pV = constant. To find temperature difference, then it's pV = nRT. This equation is for ideal gases, but it usually still works.

Not too sure abou the limit of gas expansion.

 

[pmacias]

1. Gas expansion occurs due to the kinetic energy of gas molecules. At a higher temperature, the molecules have more kinetic energy and move faster, resulting in more collisions with the container walls and causing the gas to expand to fill the available space. Even without an increase in temperature, gas molecules are constantly in motion and will still collide with the container walls, leading to expansion. The rising effect of gas in air is due to the density of the gas being lower than the surrounding air, causing it to rise. This is different from gas expansion, which refers to an increase in volume.

2. The limitation of gas expansion without an increase in temperature can be determined by the properties of the gas, such as its compressibility and density. These properties will affect how much the gas can expand before reaching its limit. Additionally, the size and shape of the container will also play a role in limiting the expansion of the gas.

3. In a vacuum, there is no surrounding air or other gases to provide resistance to the expansion of the gas. Therefore, the gas will continue to expand until it reaches its limit, regardless of the temperature. This is because there is no force acting on the gas to prevent it from expanding. However, it is important to note that the gas will not expand indefinitely, as it will eventually reach its limit due to its properties and the size of the container.