What is the pressure in a gas container that is connected to an open-end U-tube manometer if the pressure of the atmosphere is 742 torr and the level of mercury in the arm connected to the container is 8.60 cm higher than the level of mercury open to the atmosphere?

• A. 742 torr
• B. 750.6 torr
• C. 733.4 torr
• D. 828 torr

Answer: (D)

Verified step by step guidance

1. Understand that a U-tube manometer measures the pressure difference between the gas in the container and the atmospheric pressure. The difference in mercury levels indicates this pressure difference.
2. Convert the height difference of mercury from centimeters to millimeters, since pressure is often measured in torr, which is equivalent to mmHg. Use the conversion: 1 cm = 10 mm. Therefore, 8.60 cm = 86 mm.
3. Recognize that the pressure in the gas container is higher than atmospheric pressure because the mercury level is higher on the side connected to the container. This means the pressure in the container is the atmospheric pressure plus the pressure due to the mercury column.
4. Add the atmospheric pressure to the pressure exerted by the mercury column to find the total pressure in the gas container. Use the formula: \( P_{container} = P_{atmosphere} + P_{mercury} \). Here, \( P_{atmosphere} = 742 \) torr and \( P_{mercury} = 86 \) torr.
5. Calculate the total pressure in the gas container using the values from the previous step. This will give you the pressure in the container in torr.