Multiple Choice
How many grams of NaOH (molar mass = 40.0 g/mol) are there in 500 mL of a 0.175 M NaOH solution?
3. Chemical Reactions
Stoichiometry
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How many grams of water are produced when 0.23 moles of O2 react with excess H2 according to the balanced equation: 2H2 + O2 → 2H2O?
A
4.14 grams
B
9.00 grams
C
8.28 grams
D
2.07 grams
Verified step by step guidance1
Start by identifying the balanced chemical equation: 2H₂ + O₂ → 2H₂O. This equation tells us that 1 mole of O₂ produces 2 moles of H₂O.
Determine the number of moles of H₂O produced from the given moles of O₂. Since 0.23 moles of O₂ are reacting, use the stoichiometry from the balanced equation: 0.23 moles O₂ × (2 moles H₂O / 1 mole O₂) = 0.46 moles H₂O.
Calculate the molar mass of H₂O. The molar mass of H₂O is the sum of the atomic masses of hydrogen and oxygen: 2 × 1.01 g/mol (for H) + 16.00 g/mol (for O) = 18.02 g/mol.
Use the number of moles of H₂O and its molar mass to find the mass of water produced: 0.46 moles H₂O × 18.02 g/mol = mass of H₂O in grams.
Verify the calculation by ensuring that the units cancel appropriately and the final mass is consistent with the stoichiometry of the reaction.
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