It is negligible.
The atmospheric density on Mercury has not been directly measured, and may not be for many years. The thin collection of ionized gases on Mercury has an estimated surface pressure only ten-quadrillionths that of Earth (about 10-14 bar or 10-9 Pa).
If you're referring to atmospheric pressure, then it's zero.Mercury has no atmosphere.
A mercury barometer measures atmospheric pressure, which is the weight of the air pressing down on Earth's surface. It works by using a column of mercury in a sealed tube to balance the pressure of the air outside. When the air pressure increases, the mercury in the tube rises, and when the air pressure decreases, the mercury falls.
When air pressure increases, it exerts greater force on the surface of the mercury in the barometer. This additional pressure causes the mercury to rise higher in the glass tube, indicating a higher atmospheric pressure. Conversely, if the air pressure decreases, the mercury level falls. Thus, the height of the mercury column in the barometer is directly related to the atmospheric pressure.
In a mercury barometer, when air pressure increases, it exerts more force on the surface of the mercury in the reservoir, causing the mercury to rise within the tube. This rise occurs because the increased atmospheric pressure pushes down on the mercury, forcing it to ascend. Conversely, when air pressure decreases, the mercury level falls. The height of the mercury column is a direct measurement of atmospheric pressure.
When air pressure increases, the mercury in a barometer rises.
mercury
About equal to 30 inches of Mercury.
The force of Earth's atmosphere on the mercury in the dish is equal to the atmospheric pressure acting on the surface area of the mercury. This can be calculated using the formula ( F = P \times A ), where ( F ) is the force, ( P ) is the atmospheric pressure (approximately 101,325 Pa at sea level), and ( A ) is the surface area of the mercury in the dish. The pressure exerted by the atmosphere pushes down on the mercury, causing it to rise in a connected column, such as in a barometer.
A mercury barometer is a 1 meter long glass tube with the top sealed and turned upside down in a bath of mercury the pressure on the surface of the bath of mercury lifts the level of the mercury in the tube dependent on atmospheric pressure.
Planet Mercury's Surface pressure is almost none existent. This is due to its low gravity and extremely thin atmosphere that has been blasted away by solar winds.