Final answer:
To calculate the moles of oxygen in 25.45 g of CaCO3, divide the mass by the molar mass of CaCO3 (100.09 g/mol) to get the moles of CaCO3 (0.254), then multiply by 3 because each molecule contains 3 oxygen atoms, resulting in 0.762 moles of oxygen.
Step-by-step explanation:
To find out how many moles of oxygen are in 25.45 g of CaCO3, you must first determine the molecular weight of CaCO3 and then use the molar ratio of oxygen in the compound to find the moles of oxygen.
Calcium carbonate (CaCO3) contains one atom of calcium (Ca), one atom of carbon (C), and three atoms of oxygen (O). The molar mass (molecular weight) of CaCO3 can be calculated as follows:
- Calcium: 40.08 g/mol
- Carbon: 12.01 g/mol
- Oxygen: 16.00 g/mol x 3 = 48.00 g/mol
Summing these contributions, the molar mass of CaCO3 is 40.08 + 12.01 + 48.00 = 100.09 g/mol.
To find the number of moles of CaCO3, divide the mass of the CaCO3 sample by its molar mass:
Number of moles of CaCO3 = 25.45 g ÷ 100.09 g/mol = 0.254 moles of CaCO3
Since each molecule of CaCO3 contains 3 atoms of oxygen, the number of moles of oxygen is:
Number of moles of oxygen = 3 x Number of moles of CaCO3 = 3 x 0.254 = 0.762 moles of oxygen
Therefore, there are 0.762 moles of oxygen in 25.45 g of CaCO3.