Question

hydrogen gas, oxygen gas, and water vapor are collected in eudiometer. the eudiometer contains 0.00206 g of hydrogen, 0.0811 g of oxygen, and 0.0151 g of water vapor. the total pressure is 1137.1 mmhg. calculate the partial pressure (in mmhg) of hydrogen gas. round your answer to 3 significant digits.

Explanation:

Step1: Calculate moles of \(H_2\)

Molar mass of \(H_2\) is \(2\space g/mol\). Moles (\(n_{H_2}\)) = mass / molar mass = \(0.00206\space g / 2\space g/mol = 0.00103\space mol\).

Step2: Calculate moles of \(O_2\)

Molar mass of \(O_2\) is \(32\space g/mol\). Moles (\(n_{O_2}\)) = \(0.0811\space g / 32\space g/mol \approx 0.002534\space mol\).

Step3: Calculate moles of \(H_2O\) (vapor)

Molar mass of \(H_2O\) is \(18\space g/mol\). Moles (\(n_{H_2O}\)) = \(0.0151\space g / 18\space g/mol \approx 0.000839\space mol\).

Step4: Total moles (\(n_{total}\))

\(n_{total}=n_{H_2}+n_{O_2}+n_{H_2O}=0.00103 + 0.002534 + 0.000839\approx0.004403\space mol\).

Step5: Mole fraction of \(H_2\) (\(X_{H_2}\))

\(X_{H_2}=n_{H_2}/n_{total}=0.00103 / 0.004403\approx0.2339\).

Step6: Partial pressure of \(H_2\) (\(P_{H_2}\))

Total pressure (\(P_{total}\)) = \(1137.1\space mmHg\). \(P_{H_2}=X_{H_2}\times P_{total}=0.2339\times1137.1\space mmHg\approx266\space mmHg\) (rounded to 3 significant digits).

Answer:

\(266\space mmHg\)