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Chapter 5 – Practice Problems (Stoichiometry)

  1. Think back to the pound cake recipe. What possible conversion factors can you construct relating the components of the recipe?
  2. Think back to the pancake recipe. What possible conversion factors can you construct relating the components of the recipe?
  3. What are all the conversion factors that can be constructed from the balanced chemical reaction: 2H2(g) + O2(g) → 2 H2O()
  4. What are all the conversion factors that can be constructed from the balanced chemical reaction: N2(g) + 3H2(g) → 2NH3(g)?
  5. Given the chemical equation : Na(s) + H2O(ℓ) → NaOH(aq) + H2(g)
    • a. Balance the equation.
    • b. How many molecules of H2 are produced when 332 atoms of Na react?
  6. Given the chemical equation: S(s) + O2(g) → SO3(g)

    • a. Balance the equation.
    • b. How many molecules of O2 are needed when 38 atoms of S react?
  7. For the balanced chemical equation: 6H+(aq) + 2MnO4(aq) + 5H2O2(ℓ) → 2Mn2+(aq) + 5O2(g) + 8H2O(ℓ)

    • How many molecules of H2O are produced when 75 molecules of H2O2 react?
  8. For the balanced chemical reaction: 2C6H6(ℓ) + 15O2(g) → 12CO2(g) + 6H2O(ℓ)

    • How many molecules of CO2 are produced when 56 molecules of C6H6 react?
  9. Given the balanced chemical equation:       Fe2O3(s) + 3SO3(g) → Fe2(SO4)3

    • How many molecules of Fe2(SO4)3 are produced if 321 atoms of S are reacted?
  10. For the balanced chemical equation: CuO(s) + H2S(g) → CuS + H2O(ℓ)

    • How many molecules of CuS are formed if 9,044 atoms of H react?
  11. For the balanced chemical equation: Fe2O3(s) + 3SO3(g) → Fe2(SO4)3

    • Suppose we need to make 145,000 molecules of Fe2(SO4)3, how many molecules of SO3 do we need?
  12. One way to make sulfur hexafluoride is to react thioformaldehyde, CH2S, with elemental fluorine: CH2S + 6F2 → CF4 + 2HF + SF6

    • If 45,750 molecules of SF6 are needed, how many molecules of F2 are required?
  13. Construct the three independent conversion factors possible for these two reactions:
    • a. 2H2 + O2 → 2H2O
    • b. H2 + O2 → H2O2

    Why are the ratios between H2 and O2 different?

    The conversion factors are different because the stoichiometry of the balanced chemical reactions are different.

  14. Construct the three independent conversion factors possible for these two reactions:
    • a. 2Na + Cl2 → 2NaCl
    • b. 4Na + 2Cl2 → 4NaCl

    What similarities, if any, exist in the conversion factors from these two reactions?

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