Molecular Mass and Mole Concepts and Problems

1. How many moles of CO₂ are present in 22.4 g of CO₂?

1.00 mol CO₂ 0.224 mol CO₂ 0.507 mol CO₂ 2.24 mol CO₂

2. What is a mole (n)?

Mass of one molecule Number of atoms in one molecule Mass of one atom Quantity of substance containing as many elementary entities as atoms in exactly 12 grams of carbon-12

3. What is the formula for calculating molecular mass?

Sum of atomic numbers of all atoms Sum of electrons in the molecule Sum of (atomic mass of each element × number of atoms of that element) Sum of protons and neutrons

4. What is molecular mass (or molecular weight)?

The total mass of a molecule expressed in atomic mass units (amu) The mass of one atom The number of atoms in a molecule The number of molecules in a mole

5. How many oxygen atoms are present in 18.0 g of H₂O?

12.04 × 10²³ oxygen atoms 1.00 × 10²³ oxygen atoms 3.01 × 10²³ oxygen atoms 6.02 × 10²³ oxygen atoms

6. What is Avogadro’s number (Nₐ)?

9.81 1.602 × 10⁻¹⁹ 6.022 × 10²³ 3.14 × 10²³

7. What is the molar mass of an atom?

Number of atoms in a molecule Mass of 1 mole of atoms (g) Mass of 1 molecule (g) Mass of 1 atom (amu)

8. How many grams of Fe are in 2.5 moles of Fe?

55.8 g Fe 100 g Fe 250 g Fe 139.6 g Fe

9. How many atoms are in 16.3 g of S?

1.00 × 10²³ S atoms 6.02 × 10²³ S atoms 3.06 × 10²³ S atoms 2.00 × 10²³ S atoms

10. How many moles of Ne are in 10.2 g of Ne?

5.07 mol Ne 0.102 mol Ne 0.507 mol Ne 1.02 mol Ne