5.3_P - Chemistry: Molecular Nature Of Matter And Change

Question

How does a barometer work? Is the column of mercury in a barometer shorter when it is on a mountaintop or at sea level? Explain.

Step-by-Step Solution

Answer

In a mercury barometer, the atmospheric pressure is calculated from the height of the mercury column. The column of mercury in the barometer is shorter when it’s on the mountain top and longer when at sea level.

Step 1: Barometer

A Barometer is a device that is used to measure atmospheric pressure.

The most common barometer is the mercury barometer. 

Step 2: Working of the Barometer

A barometer is a long glass tube sealed at one end that is inverted in the pool of mercury with its open end.

The level of mercury rises to the point where the atmospheric pressure and gravitational force get balanced. The pressure of the surrounding atmosphere tries to push the level down of the mercury. 

So, the more will be atmospheric pressure, the lesser will be the rise of mercury in the tube.

That is how the barometer determines the atmospheric pressure.

Step 3: Level of mercury on a mountain top and sea level

At the top of a mountain, the atmospheric pressure is low. It means that the push of mercury in the barometer is low. So, the column of mercury in the barometer will be shorter.

 

On the other hand, at sea level, the atmospheric pressure is high. It means that the push of mercury in the barometer is high. So, the column of mercury in the barometer will be higher.