In the reaction \(2 \text{Ca} + \text{O}_2 \rightarrow 2 \text{CaO}\), 15.0 g of calcium oxide is produced. To find the grams of calcium used, stoichiometry is applied, resulting in approximately 10.73 g, matching option C: 10.7 g (purple).
To determine the grams of calcium used in the reaction \( \text{Ca} + \frac{1}{2}\text{O}_2 \rightarrow \text{CaO} \), we need to consider the stoichiometry of the reaction.
1. **Write the Balanced Chemical Equation:**
The balanced equation is \(2 \text{Ca} + \text{O}_2 \rightarrow 2 \text{CaO}\).
2. **Determine the Molar Mass:**
The molar mass of Ca is approximately 40.08 g/mol.
3. **Convert Given Mass to Moles:**
\[15.0 \, \text{g CaO} \times \frac{1 \, \text{mol CaO}}{56.08 \, \text{g/mol CaO}} = 0.2675 \, \text{mol CaO}\]
4. **Apply Stoichiometry:**
From the balanced equation, 2 moles of Ca are required to produce 2 moles of CaO. Therefore, the moles of Ca used are also \(0.2675 \, \text{mol}\).
5. **Convert Moles to Grams:**
\[0.2675 \, \text{mol Ca} \times 40.08 \, \text{g/mol Ca} = 10.73 \, \text{g Ca}\]
The correct answer is approximately 10.73 g, which corresponds to option C: 10.7 g (purple).
The probable question may be:
How many grams of calcium is used in this reaction, if 15.0 g calcium oxide are produced? a. 5.4 g(light green) b. 7.25 g(dark green) c. 10.7 g(purple) d. 15.0 g(dark blue). ___Ca + ___O2= ___CaO