Chapter 5, Problem 5.5P

Interpretation Introduction

Interpretation:

The reason for the level of mercury in the arm attached to the flask lower than the mercury level in the other arm in a closed-end manometer and higher in the open-end manometer is to be explained.

Concept introduction:

The Pressure of a gas can be measured with the help of a device known as a manometer.

There are basically two types of manometer. First one is closed-end manometer and the second one is open-end manometer.

In closed-end manometer, the difference in column height $\left(\Delta h\right)$ is equal to the gas pressure.

$P_{\text{gas}}=\Delta h$

In an open-end manometer, the gas pressure is being measured either by adding or subtracting $\Delta h$ from the atmospheric pressure $\left(P_{\text{atm}}\right)$ of the gas.

Case I: When $P_{\text{gas}}$ is less than $P_{\text{atm}}$ then the gas pressure is being calculated as follows:

$P_{\text{gas}}=P_{\text{atm}}-\Delta h$

Case II: When  $P_{\text{gas}}$ is more than $P_{\text{atm}}$ then the gas pressure is being calculated as follows:

$P_{\text{gas}}=P_{\text{atm}}+\Delta h$