Question

0.040 $g$ of magnesium was put into the bottom of the tube containing a dilute solution of $HCl$ and it reacted completely and formed hydrogen gas and the following data was recorded:
Air pressure in the room = 730 $mm$ $Hg$
Temperature of the water solution = 302 $K$
Vapor pressure of water at 302 $K$ = 30.0 $mmHg$
The gas collected did not fill the eudiometer. The height of the meniscus above the level of the water was 40.8 $mm$.
Correction is required for the atmospheric pressure and this is due to the difference (40.8 $mm$ ) in the height of the meniscus and the level of the water,what is that correction?

• A. 3.0 $mmHg$
• B. 6.0 $mmHg$
• C. 13.6 $mmHg$
• D. 27.2 $mmHg$
• E. 40.8 mm Hg

Answer 1

The correct option is A 3.0 $mmHg$

Correction is required for the atmospheric pressure and this is due to the 40.8 $mm$ height of the solution in the tube and above the level in the beaker.
That correction is $\frac{40.8\times 1.0}{13.6}=3.0$
Note: Here, 13.6 and 1.0 are the densities of mercury and water (in $g/mL$).