A flask 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?

Question

Quizplus · Accepted Answer

The pressure of the neon gas can be calculated by subtracting the pressure due to the height of the mercury column in the arm connected to the flask from the atmospheric pressure. The height of the mercury column in the open arm can be calculated as follows:

P = ρgh
where P is the pressure due to the height of the mercury column, ρ is the density of mercury, g is the acceleration due to gravity, and h is the height of the mercury column.

The density of mercury is 13.6 g/cm³, so the height of the mercury column can be calculated as:

h = P/(ρg) = 50. mm/(13.6 g/cm³ × 9.81 m/s²) = 0.037 m

The pressure of the neon gas can then be calculated as:

Pneon = Patm - Pmercury
where Patm is the atmospheric pressure and Pmercury is the pressure due to the height of the mercury column.

Pneon = 745 torr - (0.037 m × 13.6 g/cm³ × 9.81 m/s²)/(1 cm³/1000 mm³) × (1 atm/760 torr) = 695 torr

Therefore, the neon pressure is 695 torr.

A Flask Containing Neon Gas Is Connected to an Open-Ended