Pressure due to boiling a liquid

In summary, boiling a liquid creates pressure due to the conversion of liquid molecules into gas molecules. This pressure is directly related to the temperature of the liquid and can be calculated using the ideal gas law. As the liquid reaches its boiling point, the pressure inside the container increases, leading to the formation of vapor bubbles and eventual boiling. This pressure can also be influenced by factors such as altitude and the presence of impurities in the liquid. Overall, understanding the pressure created by boiling liquids is crucial in various industries and everyday activities, such as cooking and steam power generation.
  • #1
sc298
10
0
I am looking for an equation to determine the pressure produced by boiling a liquid.
(On the net I can only find information on the effect that pressure has on boiling point)

for example, the pressure produced by heating liquid nitrogen to 0K.

Any help would be great!

Thank you
 
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  • #2
"Boiling" means to heat a liquid to where the partial pressure of the gas is above ambient pressure. So if you confine a liquid and heat it, the pressure produced corresponds to the partial pressure or saturated vapor pressure at that temperature. You find this from a table, ie a steam table or similar. There are some on the web and any good thermo book will have a bunch of tables for different fluids in it.

Tables for Nitrogen might not go up that high - the pressures would be huge as that is well above the critical point for nitrogen (the point at which you can no longer distinguish liquid from gas - you can no longer define "boiling").
 
  • #3
You wouldn't heat Nitrogen to zero Kelvin. You would cool it.

Zero Kelvin is really cold.
 
  • #4
Lol, sorry - I saw 0K and thought 0C.
 
  • #5
russ_watters said:
Lol, sorry - I saw 0K and thought 0C.

You could talk to Redbelly about my blunder converting between Celcius and Kelvin. It went on for several posts :redface:
 
  • #6
Phrak said:
You wouldn't heat Nitrogen to zero Kelvin. You would cool it.

Zero Kelvin is really cold.

I meant heat Liquid Nitrogen to 0C (273K)
 
  • #7
Look up the phase diagram of N2. Pick the coordinate were the temperature is 273K. Where this line crosses the liquid-gas transition is the pressure you are interested in.

It looks like about 500 psi to me.
 
Last edited:
  • #8
Do you have a link to a phase diagram? I couldn't find one.
 
  • #9
Phrak said:
Look up the phase diagram of N2. Pick the coordinate were the temperature is 273K. Where this line crosses the liquid-gas transition is the pressure you are interested in.

It looks like about 500 psi to me.


Hero!

Many thanks!
 
  • #10
russ_watters said:
Do you have a link to a phase diagram? I couldn't find one.

I googled images for N2 phase diagram. I only found a crude one.
 

1. What is pressure due to boiling a liquid?

Pressure due to boiling a liquid is the force per unit area exerted by the vapor molecules above a liquid as it reaches its boiling point. This pressure is a measure of the vapor pressure of the liquid.

2. How does pressure affect boiling point?

The higher the pressure, the higher the boiling point of a liquid. This is because the increased pressure forces the molecules to stick together more tightly, making it harder for them to escape and turn into vapor. As a result, more heat is required to reach the boiling point.

3. What is the relationship between pressure and vapor pressure?

Vapor pressure is directly related to the pressure exerted on a liquid. As the pressure increases, so does the vapor pressure. This means that at higher pressures, a liquid will boil at a higher temperature.

4. How does altitude affect pressure and boiling point?

As altitude increases, the atmospheric pressure decreases. This results in a lower boiling point for liquids because the lower pressure makes it easier for the molecules to escape into vapor form. This is why it takes longer to cook food at high altitudes.

5. Can pressure due to boiling a liquid be controlled?

Yes, pressure due to boiling a liquid can be controlled by adjusting the external pressure on the liquid. This can be done using a sealed container, such as a pressure cooker, to increase the pressure and raise the boiling point of the liquid. Alternatively, a vacuum can be used to lower the pressure and decrease the boiling point.

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