In the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor.
If you burn 54.8 g of hydrogen and produce 4.90 × 102 g of water, how much oxygen reacted?
In the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor.
If you burn 54.8 g of hydrogen and produce 4.90 × 10^2 g of water, how much oxygen reacted?
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To find out how much oxygen reacted in the given combustion reaction, we need to determine the stoichiometry of the reaction. The balanced chemical equation for the combustion of hydrogen gas can be written as:
2H₂ + O₂ -> 2H₂O
From the balanced equation, we can see that for every 2 moles of hydrogen, 1 mole of oxygen reacts to produce 2 moles of water.
1 mole of hydrogen gas has a molar mass of approximately 2 g/mol, and 1 mole of oxygen gas has a molar mass of approximately 32 g/mol.
To solve this problem, we can follow these steps:
Step 1: Calculate the number of moles of hydrogen used:
Given mass of hydrogen = 54.8 g
Molar mass of hydrogen = 2 g/mol
Number of moles of hydrogen = mass / molar mass
= 54.8 g / 2 g/mol
= 27.4 mol
Step 2: Determine the number of moles of water produced:
Given mass of water = 4.90 × 10² g
Molar mass of water = 18 g/mol (approximately)
Number of moles of water = mass / molar mass
= 4.90 × 10² g / 18 g/mol
≈ 27.22 mol
Step 3: Calculate the number of moles of oxygen used:
Since the stoichiometric ratio is 2:1 between hydrogen and water, and the number of moles of hydrogen used is 27.4 mol, then the number of moles of water produced is also 27.4 mol.
Therefore, the number of moles of oxygen used = (0.5) × (27.22 mol) = 13.61 mol
Step 4: Determine the mass of oxygen used:
Mass of oxygen = number of moles × molar mass
= 13.61 mol × 32 g/mol
= 435.52 g
Therefore, the mass of oxygen that reacted in the combustion is approximately 435.52 grams.
2H2 + O2 ==> 2H2O
mols H2 = grams/molar mass
Using the coefficients in the balanced equation, convert mols H2 to mols O2.
Now convert mols O2 to grams. That's grams mols O2 x molar mass O2.