Explain the following: [5 MARKS]
(a) Thick white fumes are formed when a glass rod dipped in $N H_{4} O H$ is brought near the mouth of a bottle full of HCl gas.
(b) Dry Hydrogen chloride gas does not affect a dry strip of blue litmus but turns red in the presence of a drop of water.
(c) Hydrogen Chloride gas is not collected over water.

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Solution

a) 2 Marks
b) 2 Marks
c) 1 Mark

(a) Thick white fumes are formed when a glass rod dipped in $N H_{4} O H$ is brought near the mouth of a bottle full of HCl gas because HCl combines with ammonia to produce dense white fumes of ammonium chloride.
(\NH_3(g) + HCl(g) \rightarrow\ NH_4Cl)\

(b) Dry Hydrogen chloride gas does not affect a dry strip of blue litmus but turns red in the presence of a drop of water because dry HCl gas is a covalent compound and there are no hydronium ions present but in the presence of a drop of water, hydronium ions are produced.

(c) Hydrogen Chloride gas is not collected over water because it is highly soluble in water.

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Similar questions

Explain why :

(a) anhydrous HCl is a poor conductor while aqueous HCl is an excellent conductor.
(b) when the stopper of a bottle full of hydrogen chloride gas is opened there are fumes in the air.
(c) a solution of hydrogen chloride in water turns blue litmus red and conducts electricity, while a solution of the same gas in toluene :
(i) has no effect on litmus, and
(ii) does not conduct electricity.
(d) thick white fumes are formed when a glass rod dipped in $N H_{4} O H$ is brought near the mouth of a bottle full of HCl gas.
(e) dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in the presence of a drop of water.

(f) hydrogen chloride gas is not collected over water.

H C l

gas does not effect a dry strip of blue litmus paper but it turns red in the presence of a drop of water ?

Explain, why (or give reasons for)
(i) In the laboratory preparation of hydrogen chloride from sodium chloride, the gas can be obtained below 200°C or above. But the lower temperature is preferred.
(ii) Hydrogen chloride is not collected over water.
(iii) Hydrochloric acid cannot be concentrated above 22.2% by boiling.
(iv) HCl gas does not conduct electricity, but hydrochloric acid conducts electricity.
(v) Only a very dilute solution of hydrogen chloride in water can be concentrated by boiling the solution while a very concentrated solution would become less concentrated when boiled.
(vi) When the stopper of a bottle full of HCl gas is opened there are fumes in the air.
(vii) A solution of HCl gas in water turns blue litmus red and conducts electricity, while HCl gas dissolves in toluene and it has no effect on litmus and does not conduct electricity.
(viii) An aqueous solution of chlorine is acidic in nature.

Q. Dry hydrogen chloride gas does not turn blue litmus red whereas dilute hydrochloric acid does.

Q. Dry hydrogen chloride gas does not turn blue litmus to red whereas hydrochloric acid does. Why?

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