Question

Calculate the number of oxygen atoms and its weight in 50 g of $CaCO_3$.

Answer 1

Number of oxygen atoms: Approximately 9.03×10²³ atoms Weight of oxygen: 24 g

Answer 2

Solution Explanation:

1. Molar Mass Calculation:  Molar mass of CaCO₃ = 40 (Ca) + 12 (C) + 3×16 (O) = 100 g/mol.

2. Moles in 50 g CaCO₃:  Moles = 50 g ÷ 100 g/mol = 0.5 mol.

3. Number of Oxygen Atoms:  Each CaCO₃ contains 3 oxygen atoms.  Total moles of O atoms = 0.5 mol × 3 = 1.5 mol.  Using Avogadro’s number, number of O atoms = 1.5 mol × 6.022×10²³ = 9.033×10²³ atoms.

4. Mass of Oxygen:  Oxygen mass in one mole of CaCO₃ = 3×16 = 48 g.  Thus, in 0.5 mol, mass of oxygen = 0.5 × 48 = 24 g.