Final answer:
By comparing the height of mercury in a manometer to the known atmospheric pressure, the pressure of the gas can be determined. At 760 mm Hg atmospheric pressure, measurements equal to, less than or greater than 760 mm Hg indicate the gas pressure at sea level.
Step-by-step explanation:
When measuring the pressure of a gas with an open-end mercury manometer, the differences or equivalences in height between the mercury column in the manometer and outside atmospheric pressure can help us determine the pressure of the gas sample. If atmospheric pressure is given as 760 mm Hg, which is typical at sea level, here is how the gas pressures for each scenario can be determined:
- 760.0 mm Hg: The gas pressure is equal to atmospheric pressure, which is 760 mm Hg.
- 380.0 mm Hg: Here, the gas pressure is lower than atmospheric pressure by 380 mm Hg, resulting in a gas pressure of 380 mm Hg.
- 1520 mm Hg: This suggests the gas pressure is 760 mm Hg more than the atmospheric pressure, leading to a gas pressure of 1520 mm Hg.
- 0 mm Hg: If the manometer level is the same, thus showing no difference, it indicates there is no additional pressure exerted by the gas beyond atmospheric pressure; hence, the gas pressure would be 0 mm Hg.