# in ideal gases. how do i calculate the pressure of a liquid in a barometer given the height an the density of the liquid?'

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Expert Answers

jerichorayel | Certified Educator

Pressure can be represented in many ways. Generally it is defined as force per unit area. In chemistry, gases deal also with pressure thus rearranging the formula.

`P = F/A`

`P = (nRT)/V `

`P = rho g h`

In this case we shall use the third one.

`P = rho g h`

where:

`rho` or rho = density of the liquid `((kg)/(m^3))`

g = acceleration due to gravity `(9.8 m/s^2)`

h = height of the column (in meters)

The height of the barometer is usually in mm (millimeters), converting it to meter is usually the best way. Also, the density is shown as g/mL or g/cm^3. Necessary conversion should be done first before computing the pressure.

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