Chemistry
Explain why 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.
Answer
Dry hydrogen chloride gas does not contain any ions. Due to the absence of hydronium [H3O+] ions, it is neutral and does not affect a dry strip of blue litmus paper. On the other hand, in the presence of a drop of water, HCl dissolves in it and dissociates into hydronium [H3O+] ions and chloride ions [Cl-]
HCl + H2O ⟶ H3O+ + Cl-
The presence of hydronium [H3O+] ions makes the aqueous solution acidic and blue litmus turns red.
Related Questions
Explain why 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.
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