Answer to Question #152590 in General Chemistry for 611

Question

When the Italian physicist Evangelista Torricelli was trying to calculate the atmospheric pressure, he invented the mercury barometer (shown in the following diagram).
The main idea of this device is about balancing the pressure at the same layer between the weight of the mercury column and the weight of the air column above the open bath.

If the height of the mercury (13.6 g.cm-3) column was 60 cm at a specific place. Find:

1) The atmospheric pressure at that place.

2) The height of the air (0.001 g.cm-3) column at this place.

Answer 1

1) p_A = r_Hg x g x h = 13.6 g/cm³ x 9.8 m/s² x 60 cm = 13.6 x 10³ kg/m³ x 9.8 m/s² x 0.6 m = 79968 kg/m•s² = 79968 Pa

2) r_Hg x h_Hg = r_air x h_air

h_air = r_Hg x h_Hg / r_air = 13.6 g/cm³ x 60 cm / 0.001 g/cm³ = 816 000 cm = 8.16 x 10³ m