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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multipleQuestions newQuestion A reaction is 2 H2 + O2 -> 2 H2O. If 4.0 g of H2 reacts completely with excess O2, what mass of H2O is produced? Show the worked solution. newAnswer 36 g of H2O is produced. Worked Solution: 1. 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 2. 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 3. Use the mole ratio from the balanced equation to find moles of H2O: From the equation 2 H2 + O2 -> 2 H2O, the mole ratio of H2 to H2O is 2:2, or 1:1. Moles of H2O = Moles of H2 = 1.984 mol H2O 4. 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 = 35.74 g H2O 5. Round to appropriate significant figures: The given mass (4.0 g) has two significant figures, so the answer should also be rounded to two significant figures. Mass of H2O = 36 g