Answer:
1.81 x 10²² atoms O
Explanation:
To find the number of oxygen atoms, you need to (1) convert grams CaCO₃ to moles CaCO₃ (via molar mass), then (2) convert moles CaCO₃ to moles O (via mole-to-mole ratio from formula subscripts), and then (3) convert moles O to atoms O (via Avogadro's Number). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the amount of sig figs in the given value.
Molar Mass (CaCO₃): 40.078 g/mol + 12.011 g/mol + 3(15.998 g/mol)
Molar Mass (CaCO₃): 100.083 g/mol
1 CaCO₃ = 1 Ca and 1 C and 3 O
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
1.00 g CaCO₃ 1 mole 3 moles O 6.022 x 10²³ atoms
---------------------- x ------------------ x ---------------------- x ------------------------------ =
100.083 g 1 mole CaCO₃ 1 mole
= 1.81 x 10²² atoms O
