Question

If the sample flask in Figure P5.12 is open to the air, what is the atmospheric pressure (in atm)?

Short answer

The atmospheric pressure is 0.966 atm.

Step-by-step solution

Determination of the atmospheric pressure

The atmospheric pressure is equal to the difference in height of the mercury column.

$∆\text{h} \text{=} {\text{P}}_{\text{atmospheric}}$

Now, height is,

$∆\text{h} \text{=} 0.734 \text{m}$

Convert m into mm,

$$\begin{gathered} 1.0 \text{m = 1000} \text{mm} \\ \Rightarrow \text{0.734} \text{m} \text{=} \text{734} \text{mm} \end{gathered}$$

So, the atmospheric pressure is 734 mmHg.

Conversion of unit from mmHg to atm 

1 atm = 760 mmHg

Now, the pressure is,

$\text{734} \text{mmHg} \times \frac{\text{1} \text{atm}}{\text{760} \text{mmHg}} \text{=} \text{0.966} \text{atm}$

Thus, the atmospheric pressure is 0.966 atm.