Aflask containing neon gas is connected to an open-ended mercury manometer. the open end is exposed to the atmosphere, where the prevailing pressure is 745 torr. the mercury level in the open arm is 50. mm below that in the arm connected to the flask of neon. what is the neon pressure, in torr?

Gas pressure = 695 torr

Explanation:

If the mercury level to an open-ended of manometer is higher than the mercury level of the arm connected to the gas flask, then atmospheric pressure is lower than gas pressure.

Gas pressure = Atmospheric pressure + Δh

where  Δh is the difference in mercury level of both arm.

And if the mercury level to an open-ended of manometer is lower than the mercury level of the arm connected to the gas flask, then atmospheric pressure is greater than gas pressure.

Gas pressure = Atmospheric pressure - Δh

Given data:

Atmospheric pressure = 745 torr = 745 mmHg (Because 1 torr = 1 mmHg)

Δh = 50 mm

As in our case, mercury level to an open-ended of manometer is lower than the mercury level of the arm connected to the neon gas flask. So,

Gas pressure = Atmospheric pressure - Δh

Gas pressure = 745 - 50

Gas pressure = 695 mm Hg

Gas pressure = 695 torr

The neon pressure : 695 torr

The pressure on the gas in a confined space is measured using a manometer. One that is used is an open manometer

The manometer is open in the shape of a U tube and is filled with mercury liquid with both ends open. The other end is related to external pressure while the other end is connected to the room where the pressure will be measured

The height of the mercury will change when the end of the tube is connected to the room

The room for the problem above is A flask containing neon gas

The equation used is

P bar = atmospheric pressure

Δh = difference in mercury height

The + sign if the mercury surface at the tip is associated with the outside water is higher and vice versa, the sign - if the mercury surface is lower

The statement of the question states that the surface / mercury level at the end connected to the system / room / flask is higher than the open end, by 50 mm, so the amount of gas pressure:

Because 1 torr = 1 mmHg then

P gas = P bar - h

P gas = 745 mmHg - 50 mm

P gas = 695 mmHg = 695 torr

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