Question detail
How many grams of CaCO3 are needed to produce 0.5 moles of CO2 in the reaction CaCO3 → CaO + CO2?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Use of amount of substance in relation to masses of pure substances
Question
- A. 50 g
- B. 100 g
- C. 150 g
- D. 200 g
Answer
50 g
Explanation
From the balanced equation, 1 mole of CaCO3 produces 1 mole of CO2. Therefore, 0.5 moles of CO2 require 0.5 moles of CaCO3. The molar mass of CaCO3 is 100 g/mol, so 0.5 moles will weigh 0.5 * 100 g = 50 g.
Common mistake
Confusing Mass and Moles
Students often confuse the mass of a substance with the number of moles when calculating the masses of reactants from a balanced symbol equation.
To fix this, remember to use the formula that relates mass, moles, and relative formula mass: mass = moles x Mr. Ensure you calculate the number of moles first before converting to mass. Keep the correction anchored to Amounts of substances in equations (HT only); check formula, substitution, calculation, final answer, and unit where relevant.
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