Pressure; which is which?

Question

If I have two bottles, 1 with all the air sucked out and 1 with more air pumped in, which 1 is at a higher pressure and which 1 is at a lower pressure in comparison with the surrounding normal air pressure?

Answer 1

To answer this question, observe the following formula:

PV=nRT

When you take air out, you are removing some moles of whatever substance from the bottle. When you pump air in, you are increasing the number of moles of whatever substance. According to the equation above, when you increase the number of moles, you increase the pressure in the bottle, and vice versa. Therefore, the bottle with the most pressure is the bottle that you pumped air into.

Answer 2

The one with more air pumped in will be at a greater pressure realtive to the bottle with the air sucked out. Why? Because pressure is measured by the amound of force being applied over a surface area between two volumes. If you have more air in one medium, there will be more air to push against the walls of the medium trying to equalize with the surrounding medium.

The one with the air sucked out is at a lower pressure relative to the surrounding atmosphere because there is less air and the air surrounding the bottle is trying to equalize and fill the missing space.

Do you understand? If not, contact me through answers and I can explain with more detail.

Answer 3

If you mean the "internal" pressure then it's as follows,

1. If the bottle with air "sucked" out has a lower density of air inside than outside, and is at the same temperature as the air outside, then its pressure is lower.

2. If the bottle with the air "pumped" into to is has a higher density of air than outside, and is at the same temperature as the air outside, then its pressure is higher.

Answer 4

A pump creates pressure. If you pump air in it has a higher pressure.
A total vacuum has all the air sucked out and zero pressure like out in space.
Vacuums suck like a vacuum cleaner.