Air pressure and temperature increase

[blah354]

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if someone inflates his car tire and waits for a couple of hours at which time the air temperature rises 10 degrees celcius. How does the air pressure within the tires compare to what it was when they were inflated?


the answer involves P/T initial=P/T final and that aire pressure is greater than when it was inflated. why? i thought if T increases then P would decrease

 

[loveoforganic]

Honestly, I haven't gotten to this section of content review yet and don't remember the formula, but if you think about it logically, you're adding kinetic energy to the particles with increasing temperature, so pressure (collisions with the wall) should increase. You could also think, hot air is less dense than cold air, so it must try to take up more space.

 

[FutureInternist]

Honestly, I haven't gotten to this section of content review yet and don't remember the formula, but if you think about it logically, you're adding kinetic energy to the particles with increasing temperature, so pressure (collisions with the wall) should increase. You could also think, hot air is less dense than cold air, so it must try to take up more space.

👍

 

[Dr Gerrard]

P/T is a constant. Gay-Lussac's Law

So if pressure increases, temperature must increase in order to keep the ratio a constant.

If pressure = 1 and temperature =1 initially, when you raise pressure to 2, temperature also raises to 2 in order to keep the ratio 1.

Don't know if this answers your question because I did not really understand it.

Also, this is derived from PV=nRT.
When V, n, and R are constant, P/T=nR/V=a constant.

 

[blah354]

thank you for your quick answers! they were helpful.

 

[Steelersfan2009]

if you understand the ideal gas law and not just memorize the formula, you should understand that Pressure and Volume would have inverse relationship, while Pressure and Temperature would have a direct relationship.. Be able to know what these graphs would look like as well as I have seen these appear on numerous MCAT practice problems.

 

[Vanguard23]

Be careful though. As EK warns, if the container can perform PV work(expand like a tire can) then increasing the temperature may not increase the pressure as the volume expands and pressure remains relatively the same. Which makes sense given it's doing work by expanding from the internal energy.
Is that correct?

 

[chemtopper]

Here it is very simple
PV=nRT is the ideal gas
Now when V and n are constant
P = KT where k= nR/V
so from here you can say that P is directly proportional to T .It means if T increases ,P will also increase if V and n(amount of gas) are kept constant.