Some harder problem for practice in STOICHIOMETRY

1. From the following reaction sequence,
CaC₂ + H₂O ® CaO + C₂H₂
C₂H₂ + H₂ ® C₂H₄
nC₂H₄ ® (C₂H₄)_n
Calculate the mass of polyetheylene which can be produced from 10 kg of CaC₂ Ans. 4375g

2. From the following series of reactions,
Cl₂ + 2KOH ® KCl + KClO + H₂O
3KClO ® 2KCl + KClO₃
4KClO₃ ® 3KClO₄ + KCl
Calculate the mass of chlorine needed to produce 100 g of KClO₄. Ans. 204.5 g

3. Crude calcium carbide is made in an electric furnace by the following reaction :
CaO + 3C ® CaC₂ + CO
The product contains 85% of CaC₂ and 15% of unreacted CaO.
(a) How much CaO is to be added to the furnace charge for each 1000 kg of CaC2 (pure) produced?
(b) How much CaO is to be added to the furnace charge for each 1000 kg of crude product ?
Ans. (a) 1041.5 kg ; (b) 893.7 kg

4. From the following reactions, 2CoF₂ + F₂ ® 2CoF₃
(CH₂)_n + 4n CoF₃ ® (CF₂)n + 2nHF + 4n CoF₂
calculate how much F₂ will be consumed to produce 1 kg of (CF₂)_n. Ans. 1.52 kg

5. A mixture containing KClO₃, KHCO₃, K₂CO₃ and KCl was heated, producing CO₂, O₂ and H₂O gases according to the following equations :
2KClO₃(s) ® 2KCl(s) + 3O₂
2KHCO₃(s) ® K₂O(s) + H₂O(g) + 2CO₂(g)
K₂CO₃(s) ® K₂O(s) + CO₂(g)
The KCl does not react under the conditions of the reaction. If 100.0 g of the mixture produces 1.80 g of H₂O, 13.20 g of CO2 and 4.0 g of O₂, what was the composition of the original mixture ? Ans. (KClO₃ : 10.2 g, KHCO₃ : 20g, K₂CO₃ : 13.8 g

6. A natural gas sample contains 84% (by volume) of CH₄, 10% of of C₂H₆ , 3% of C₃H₈ and 3% of N₂. If a series of catalytic reactions could be used for converting all the carbon atoms of the gas into butadiene, C₄H₆, with 100% efficiency, how much butadiene could be prepared from 100 g of the natural gas ? Ans. 82 g