# Calculating Vliq/Vg for Water at 25°C

• chloromethane
In summary, the task is to use the ideal gas law to calculate the volume of liquid water (Vliq) as a fraction of the volume of water vapour (Vg) at 25°C and 1atm. The density of water at 25°C and 1atm is 0.997 g/cm³ and the vapour pressure is 3.1691 kPa. The ideal gas law equation PV=nRT can be used to calculate Vg, which is 0.0245m³ for one mole of water vapour. However, it is unclear how to proceed with calculating Vliq and comparing it to Vg. The use of the Clausius-Clapeyron equation may
chloromethane

## Homework Statement

'Look up the density and vapour pressure of water at 25°C, and use the ideal gas law to calculate Vliq as a fraction of Vg for one mole of water at 25°C'

Ok so, Density of water at 25°C & 1atm is: 0.997 g/cm³.
The vapour pressure of water at 25°C and 1atm is: 3.1691 kPa

## Homework Equations

The ideal gas law: PV=nRT
Also, I think perhaps the Clausius-Claperon equation might be used?!

## The Attempt at a Solution

I think the question is a little ambiguous, so I am unsure of how to approach this question.

For a start, I can use the ideal gas equation to work out the volume of one mole of water vapour at 25°C and 1atm:

V=nRT/P= (1mole)x(8.314J/Mol.K)x(298K)/101,325Pa= 0.0245m³

However, I'm stuck now as to what is the next logical step!

Is the question asking me to work out the volume of liquid water at 25°C and 1atm, and then compare it to the volume of water vapour at 25°C and 1atm? If so, I'm not sure how to go about doing that! Any help would be much appreciated!

## What is Vliq/Vg for water at 25°C?

Vliq/Vg is the volume of liquid water at 25°C divided by the volume of water vapor at 25°C. It is a ratio that is used to describe the equilibrium between liquid and vapor phases of water at a specific temperature and pressure.

## Why is calculating Vliq/Vg important?

Calculating Vliq/Vg allows us to understand the behavior of water at different temperatures and pressures. This information is important in various fields such as meteorology, environmental science, and engineering, as it helps us predict and control the movement of water in different systems.

## How do you calculate Vliq/Vg for water at 25°C?

To calculate Vliq/Vg for water at 25°C, you would need to know the volume of liquid water and the volume of water vapor at that specific temperature and pressure. Then, divide the volume of liquid water by the volume of water vapor to obtain the Vliq/Vg ratio.

## What are the units for Vliq/Vg?

Vliq/Vg is a dimensionless ratio, meaning it has no units. This is because it is a ratio of two volumes, which cancel out each other's units.

## How does Vliq/Vg change with temperature and pressure?

Vliq/Vg changes with temperature and pressure because it is a measure of the equilibrium between liquid and vapor phases of water. As temperature and pressure change, the volume of water in each phase also changes, thus affecting the Vliq/Vg ratio. Generally, as temperature increases, Vliq/Vg decreases, and as pressure increases, Vliq/Vg increases.

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