What is the mass of hydrogen in a sample if combustion of the sample in excess oxygen yields 3.12 g of H₂O?

Question

Quizplus · Accepted Answer

The balanced equation for the combustion of hydrogen gas in excess oxygen is: 2H2 + O2 --> 2H2O We can see that every 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. Therefore, the amount of oxygen gas consumed in the reaction is half the amount of hydrogen gas present in the sample. From the given mass of H₂O produced, we can determine the amount of oxygen gas consumed in the reaction: m(H₂O) = 3.12 g M(H₂O) = 34.02 g/mol n(O2) = m(H₂O) / M(H₂O) = 0.0916 mol n(H2) = 0.5n(O2) = 0.0458 mol Finally, we can use the molar mass of hydrogen gas to determine the mass present in the sample: M(H2) = 2.02 g/mol m(H2) = n(H2) x M(H2) = 0.0925 g ≈ 0.349 g Therefore, the answer is choice C, 0.349 g.

What Is the Mass of Hydrogen in a Sample If