Multiple Choice
How many molecules are in 68.6 moles of CO₂?
2. Atoms & Elements
Mole Concept
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How many moles of oxygen atoms are present in 25.45 g of CaCO₃?
A
0.254 moles
B
0.254 moles
C
0.254 moles
D
0.254 moles
Verified step by step guidance1
Identify the chemical formula of calcium carbonate, which is CaCO₃. This compound contains one calcium (Ca) atom, one carbon (C) atom, and three oxygen (O) atoms.
Calculate the molar mass of CaCO₃ by adding the atomic masses of its constituent elements: Ca (40.08 g/mol), C (12.01 g/mol), and O (16.00 g/mol). The molar mass of CaCO₃ is calculated as: 40.08 + 12.01 + (3 × 16.00).
Determine the number of moles of CaCO₃ in 25.45 g by using the formula: \( \text{moles of CaCO₃} = \frac{\text{mass of CaCO₃}}{\text{molar mass of CaCO₃}} \). Substitute the given mass and the calculated molar mass into this formula.
Since each molecule of CaCO₃ contains three oxygen atoms, multiply the moles of CaCO₃ by 3 to find the moles of oxygen atoms: \( \text{moles of O atoms} = 3 \times \text{moles of CaCO₃} \).
Review the calculation to ensure all steps are correctly followed and the units are consistent, confirming the number of moles of oxygen atoms present in the given mass of CaCO₃.
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