Composition Stoichiometry Extra Practice

Part 1 – Mass, Moles, and Molecules

1. Calculate the number of moles in a 78.25 g sample of NaCl.
2. Calculate the mass of 1.84 moles of MgCl₂.
3. Calculate the number of moles in a 0.153 g sample of H₂SO₃.
4. Calculate the mass of 0.0194 moles of neon gas.
5. Calculate the number of molecules in the neon gas sample above.
6. Calculate the number of hydrogen atoms in 18.64 g water (H₂O).

Part 2 – Percent Composition

Calculate the percent mass of every element in each of the following compounds:

1. KClO₄
2. Na₂Cr₂O₇
3. CuSO₄ · 5H₂O
4. MgF₂
5. H₂O₂
6. CH₂(NH₂)₂