Chapter 8, Problem 40E

Interpretation Introduction

Interpretation:

The pressure in the flask of manometer should be determined in units of torr and atm when the manometer shows a reading of 20.0 inches.

Concept Introduction:

The manometer is a devise used measure the pressure of a gas. The pressure of gas is determined by the value of ‘h’ shown by the manometer. This ‘h’-value is added or subtracted with atmospheric pressure to determine the pressure of gas.

If the flask side mercury level is decreased after the filling of gas, then the ‘h’-value will be added to atmospheric pressure to get the pressure of gas.

$\text{Atmospheric pressure }\text{=}\text{ 760 mm Hg /torr}$

The pressure equivalent of ‘h’ value is,

    $\text{h}\text{=}\text{1}\text{inch}\text{=}\text{25}\text{.4}\text{mm}\text{Hg}$

Pressure of a substance can be stated in various units. The units of pressure are interconvertible. The relations between the units of pressure are,

• Since the unit mm Hg and the unit torr is used interchangeably.

$1\text{mm}\text{Hg}\text{=}1\text{torr}$

• Conversion of 1 torr into atm is,

              $\text{1}\text{mm}\text{Hg}\text{=}\frac{\text{1}}{\text{760}}\text{atm }$