Question

An open-end manometer is filled with mercury so that each side has a height equal to 11.8 cm. If the atmospheric pressure is 776 torr on a given day, what are the approximate maximum and minimum pressures that this manometer can measure?

Answer 1

The maximum and minimum pressures measurable by the open-end manometer with mercury columns starting at 11.8 cm under atmospheric conditions of 776 torr would be 776 torr and 540 torr, respectively.

Step-by-step explanation:

An open-end manometer is used to measure gas pressure relative to atmospheric pressure. It consists of a U-shaped tube filled with mercury (Hg), with one end open to the atmosphere and the other connected to the gas sample. The gas pressure can be determined by adding or subtracting the difference in mercury levels from the atmospheric pressure.

On a day when the atmospheric pressure is 776 torr, and the mercury column on each side of the manometer is at 11.8 cm, the maximum pressure that can be measured is when the mercury is completely displaced from the open end (zero height). This would be just atmospheric pressure, as there is no height difference to add. So the maximum pressure measurable is 776 torr. The minimum pressure would be when the mercury columns differ by the full 11.8 cm on both sides, which means a difference of 23.6 cm or 236 mmHg less than atmospheric pressure. Therefore, the minimum would be 776 torr - 236 mmHg, which is approximately 540 torr.

Answer 2

Using an open-end manometer filled with mercury, the approximate maximum pressure that can be measured is 1012 torr, and the approximate minimum pressure is 540 torr, assuming an atmospheric pressure of 776 torr.

Step-by-step explanation:

The given problem involves an open-end manometer filled with mercury (Hg) that can be used to measure gas pressure. The atmospheric pressure is given as 776 torr, and we need to find the approximate maximum and minimum pressures the manometer can measure. When both sides of the manometer are equal at a height of 11.8 cm, this indicates that the pressure exerted by the gas is the same as atmospheric pressure. To calculate the maximum and minimum pressures, consider the scenario in which all the mercury is displaced to one side or the other.

• The maximum pressure that can be measured occurs when the mercury is completely displaced from the side open to the atmosphere, resulting in the gas side being 23.6 cm higher than the atmospheric side. This means an added pressure of 236mm Hg to the atmospheric pressure; hence the maximum pressure measurable is 776 torr + 236 torr = 1012 torr.
• The minimum pressure measurable occurs when the mercury is completely displaced from the gas side, resulting in the atmospheric side being 23.6 cm higher than the gas side. This means a reduction of 236mm Hg from the atmospheric pressure; hence the minimum pressure measurable is 776 torr - 236 torr = 540 torr.