Question

magnesium metal is reacted with hydrochloric acid to produce hydrogen gas. a sample of hydrogen gas is collected over water in a eudiometer at 28.0 °c. the atmospheric pressure is 811. mmhg. determine the pressure (in atm) of the hydrogen gas produced. round your answer to 3 significant digits.
temperature (°c) | water vapor pressure(mmhg)
20 | 17.5
22 | 19.8
24 | 22.4
26 | 25.2
28 | 28.3
30 | 31.8
note: reference the conversion factors for non - si units table for additional information.

Explanation:

Step1: Find water vapor pressure at 28°C

From the table, at 28°C, water vapor pressure is 28.3 mmHg.

Step2: Calculate hydrogen gas pressure

Total atmospheric pressure \( P_{total} = 811 \) mmHg.
Pressure of hydrogen \( P_{H_2} = P_{total} - P_{H_2O} \)
\( P_{H_2} = 811 - 28.3 = 782.7 \) mmHg.

Step3: Convert mmHg to atm

Use conversion factor: \( 1 \) atm \( = 760 \) mmHg.
\( P_{H_2} (atm) = \frac{782.7}{760} \approx 1.03 \) atm (rounded to 3 significant digits).

Answer:

1.03 atm