How many moles of water are in 36 grams of H2O? (molar mass 18 g/mol)
Answer and explanation
Correct answer: C. 2 moles
- Step 1: Moles = mass / molar mass. Step 2. 36 / 18 = 2. Answer: 2 moles. Why not the others: 0.5 moles results from inverting the molar mass calculation (18 / 36); 18 moles confuses the molar mass with total moles; and 4 moles is double the true stoichiometric quantity.
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