Question

A container has a volume of `15 L` and holds `9 mol` of gas. If the container is compressed such that its new volume is `8 L`, how many moles of gas must be released from the container to maintain a constant temperature and pressure?

Answer 1

See below

Explanation:

`v= 15L`
`n = 9`

According to Ideal Gas equation

`PV = nRT-----------(I)`

Where
`R` is a constant whose value depends
`P` is pressure
`V` is volume
`n` is moles
`T` is temperature

`P15 = 9TR`

Now moving on to the second condition

`v = 8L`
`n = ?`

`PV = nRT`

`P8 = nRT --------- (II)`

Dividing (I) and (II)

We have,

`(P15)/(P8) = (9RT)/(nRT)`

Since the given conditions are same for both the cases, These can be canceled out..... So we are left with

`(15)/(8) = (9)/(n)`

`72/15 = n`

`n = 4.8`

Therefore 9 - 4.8 moles need to be removed

i.e `4.2 mol` to maintain the same pressure and temperature.