[T]

Hello,

The question is:

Butane has a vapour pressure of 47.156 kPa at 253 K, and 149.03 kPa at 283 K. Is butane gaseous or non-gaseous under the following conditions:

Temp. = 253 K      Pressure = 1 atm
Temp. = 253 K      Pressure = 2 atm
Temp. = 283 K      Pressure = 1 atm
Temp. = 283 K      Pressure = 2 atm

So firstly, I have searched what vapour pressure means. And from what I read, vapour pressure is the pressure of the vapour of a liquid at equilibrium in a closed system. And can only affected by temperature.

So since butane has a vapour pressure of 47.156 kPa at 253 K, at 253 K and 1 atm the vapour pressure of butane would still be 47.156 kPa. However, I am not sure how the external pressure would affect the physical state of butane. Could someone explain this? Also does the 1 atm mean that in a closed system, the pressure in it is 1 atm?

Thanks

[mjc123]

What happens when the vapour pressure of a liquid is greater than the external pressure?

[T]

The liquid boils doesn't it?

So when butane has:
Temp. = 283 K      Pressure = 1 atm
It would be gaseous?

And for the others it would be non-gaseous?

[mjc123]

Correct

[T]

Thanks mjc123