High School

A sample of oxygen was collected in a tube over water, resulting in a mixture of oxygen gas and gaseous water (steam). The total pressure of the gas mixture is 760 torr. If the pressure of gaseous water is 23.8 torr, what is the pressure of the pure oxygen?

A) 783 torr
B) 740 torr
C) 736 torr
D) 99.8 torr

Answer :

Final answer:

To find the pressure of the pure oxygen, the water vapor pressure is subtracted from the total pressure of the gas mixture, leading to a pressure for the oxygen of 736.2 torr, which when rounded to the nearest whole number is 736 torr. Therefore, the correct option is C.

Explanation:

To calculate the pressure of the pure oxygen in the collected sample, we can use Dalton's Law of Partial Pressures. This law states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of individual gases. According to the data provided, the total pressure of the gas mixture is 760 torr, and the pressure of the gaseous water (water vapor or steam) is 23.8 torr. Therefore, the pressure of the oxygen can be found by subtracting the water vapor pressure from the total pressure:

Total pressure = Pressure of oxygen + Pressure of water vapor

Pressure of oxygen = Total pressure - Pressure of water vapor

Pressure of oxygen = 760 torr - 23.8 torr

Pressure of oxygen = 736.2 torr

However, since the options given are all rounded to the nearest whole number, the answer is rounded to 736 torr. Therefore, the correct answer is C) 736 torr.

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