并没有什么用的高中题……（太！简！单！了！）

选自1968年第一届ICHO（世界奥林匹克化学竞赛真题）

 

 

PROBLEM 1

A mixture of hydrogen and chlorine kept in a closed flask at a constant temperature was irradiated by scattered light. After a certain time the chlorine content decreased by 20 % compared with that of the starting mixture and the resulting mixture had the composition as follows: 60 volume % of chlorine, 10 volume % of hydrogen, and 30 volume % of hydrogen chloride.

Problems: 1.1 What is the composition of the initial gaseous mixture?

1.2 How chlorine, hydrogen, and hydrogen chloride are produced?

 

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SOLUT ION

1.1 H₂ + Cl₂ → 2 HCl

30 volume parts of hydrogen chloride could only be formed by the reaction of 15

volume parts of hydrogen and 15 volume parts of chlorine. Hence, the initial

composition of the mixture had to be:

Cl₂: 60 + 15 = 75 %

H₂: 10 + 15 = 25 %

1.2 Chlorine and hydrogen are produced by electrolysis of aqueous solutions of 

NaCl: NaCl(aq) → Na⁺(aq) + Cl^- (aq)

anode: 2 Cl^- – 2 e ^-→ Cl2

cathode: 2 Na⁺ + 2 e^- → 2 Na

2 Na + 2 H₂O → 2 NaOH + H₂

Hydrogen chloride is produced by the reaction of hydrogen with chlorine.