20. A gas is collected over water at 24.0 °C and 745 mm Hg. Use the water vapor pressure table below to calculate the pressure of the dry gas alone. Show your work and round to
the proper number of significant digits. Do not put the unit.
T(0) P (mm Hg)
21 18.6
22 19.8
23
21.1
24 22.4
25 23.8
26 25.2
27 26.7
28 28.3
29 30.0
30 31.8
35 42.2

Pressure of dry gas = 722.6 mmHg

Explanation:

From the question given above, the following data were obtained:

Measured pressure = 745 mmHg

Water vapor pressure at 24.0 °C = 22.4 mmHg

Pressure of dry gas =?

The pressure of dry gas can be obtained as follow:

Measured pressure = pressure on dry gas + water vapor pressure

745 = pressure of dry gas + 22.4

Collect like terms

Pressure of dry gas = 745 – 22.4

Pressure of dry gas = 722.6 mmHg

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