# Ideal gas probs

## Main Question or Discussion Point

Hi all, I dont know if this is in the right place, but anyway hopefully someone maybe able to help.

Im stuck on a couple of questions I have to answer:

A room has the dimensions 15m long, 7m wide and 3.3m high, Assuming the air in the room is 11degC, 108394Pa and has a gas constant of 0.2870 Kj/kg K, Calculate:

a) The volume of air in the room (m^3) This I have at being 364.5 m^3

b) The mass of air in the room, I have this to be 460.5kg

Now this is the part i am stuck on:

Assume now that the temperature has changed to 24degC, and the gas constant remains constant, calculate

The mass of air in the room(kg)
The pressure of air in the room (Pa)

Im not sure how to go about find these out, because to find the mass you need the pressure and vice versa( or so I understand).

If anyone can enlighten me on how to achieve the unknowns via another method it would be greatly appreciated.

Many thanks.

Hi all, I dont know if this is in the right place, but anyway hopefully someone maybe able to help.

Im stuck on a couple of questions I have to answer:

A room has the dimensions 15m long, 7m wide and 3.3m high, Assuming the air in the room is 11degC, 108394Pa and has a gas constant of 0.2870 Kj/kg K, Calculate:

a) The volume of air in the room (m^3) This I have at being 364.5 m^3

b) The mass of air in the room, I have this to be 460.5kg

Now this is the part i am stuck on:

Assume now that the temperature has changed to 24degC, and the gas constant remains constant, calculate

The mass of air in the room(kg)
The pressure of air in the room (Pa)

Im not sure how to go about find these out, because to find the mass you need the pressure and vice versa( or so I understand).

If anyone can enlighten me on how to achieve the unknowns via another method it would be greatly appreciated.

Many thanks.

You do?

Assume now that the temperature has changed to 24degC, and the gas constant remains constant, calculate

The mass of air in the room(kg)
The pressure of air in the room (Pa)

PV=nRT
if the room is a closed system, then the mass remains unchanged.
if it is not, some mass of molecules are expelled ...

Nice one, it makes sense now!