# Boiling point at a certain pressure

• kthouz
In summary, the conversation discusses the equations used to calculate the boiling point of a liquid at a pressure different from standard temperature. The ideal gas law is not the correct equation to use and the Clausius-Clapeyron equation should be used instead. However, one challenge is finding the heat of vaporisation.
kthouz
How can one calculate the boiling of a liquid at a pressure different from standard temperature?

Am trying to do it using the ideal gas equation,

(PV)/T=(P'V')/T'
Where P is the STP, V is 22.4l, T= boiling point at STP, P'= new pressure, V' is the new volume and T' is to be found. But is it easy to find V'.

But I found another equation of Clausius-Clapeyton which involves the heat of vaporisation. Using this equation, the problem is finding the heat of vaporisation. Can anyone help me?

The ideal gas law is the wrong equation to use (since it has nothing to do with vapor-liquid equilibrium) but the Clausius-Clapeyron equation is the correct equation to use (since it is derived by specifically focusing on vapor-liquid equilibrium thermodynamics).

## 1. What is boiling point at a certain pressure?

The boiling point at a certain pressure is the temperature at which a liquid turns into a gas at that specific pressure.

## 2. How does pressure affect boiling point?

In general, an increase in pressure will result in a higher boiling point, while a decrease in pressure will result in a lower boiling point. This is because pressure affects the vapor pressure of the liquid, which is the pressure exerted by the gas molecules above the liquid.

## 3. What is the relationship between boiling point and elevation?

As elevation increases, the atmospheric pressure decreases, resulting in a lower boiling point. This is why water boils at a lower temperature at higher elevations, such as in mountains.

## 4. Can the boiling point of a substance change at a constant pressure?

No, the boiling point of a substance remains constant at a specific pressure, unless there is a change in the composition of the substance or the pressure itself.

## 5. How is boiling point used in chemistry?

The boiling point of a substance is an important physical property that can be used to identify and classify different substances. It is also used in various industrial processes, such as distillation, to separate and purify different components of a mixture.

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