This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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When 4.0 g of H2 reacts completely with O2, 36 g of H2O is produced. Full Worked Solution: 1. Write the balanced chemical equation: The reaction between hydrogen gas (H2) and oxygen gas (O2) to form water (H2O) is: 2H2(g) + O2(g) → 2H2O(l) 2. Calculate the molar masses: Molar mass of H2 = 2 × 1.008 g/mol = 2.016 g/mol Molar mass of H2O = (2 × 1.008 g/mol) + 15.999 g/mol = 18.015 g/mol 3. Convert the given mass of H2 to moles: Moles of H2 = Mass of H2 / Molar mass of H2 Moles of H2 = 4.0 g / 2.016 g/mol ≈ 1.984 mol H2 4. Use the mole ratio from the balanced equation to find moles of H2O: From the balanced equation, 2 moles of H2 produce 2 moles of H2O. This is a 1:1 mole ratio. Moles of H2O = Moles of H2 Moles of H2O ≈ 1.984 mol H2O 5. Convert moles of H2O to mass: Mass of H2O = Moles of H2O × Molar mass of H2O Mass of H2O = 1.984 mol × 18.015 g/mol Mass of H2O ≈ 35.74 g 6. Round to the correct number of significant figures: The given mass (4.0 g) has two significant figures. Therefore, the final answer should also be rounded to two significant figures. Mass of H2O ≈ 36 g Final Answer: 36 g of H2O is produced.