What would happen if
(i) Calcium oxide is used to dry hydrogen chloride.
(ii) Concentrated hydrochloric acid is kept open.
(iii) Hydrogen chloride prepared in laboratory, is passed through water, using a delivery tube.

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Solution

(i) Although calcium oxide is a very good drying agent, it cannot be used to dry HCl gas because it reacts with HCl to form calcium chloride.

CaO(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l)
Calcium
chloride
(ii) Hydrochloric acid is made by dissolving HCl gas in water. However, the vapour pressure of HCl gas in a solution is greater than that of the ambient pressure. Because the pressure of HCl gas at the surface of the liquid is greater than that of the atmosphere, it escapes in the gaseous state into the atmosphere, when left open. This process continues until the pressure of the acid in the bottle equals the pressure of the atmosphere.

(iii) When hydrogen chloride, which is prepared in the laboratory, is passed through water using a delivery tube, it reacts rapidly with water to form hydrochloric acid and is completely ionised.

HCl(g) + H₂O(l) → H₃O⁺(aq) + Cl⁻(aq)

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Q. Hydrochloric acid is prepared in the laboratory by passing hydrogen chloride directly through water.

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(ii) What arrangement is done to dissolve hydrogen chloride gas in water?

(a) Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas.
(b) Give the balanced equation for the reaction.
(c) Name the drying agent used in drying hydrogen chloride gas.
(d) Phosphorus pentoxide and calcium oxide are good drying agents but they cannot be used to dry hydrogen chloride gas. Why?

(a) What is the property of concentrated sulphuric acid which allows it to be used in the preparation of hydrogen chloride and nitric acid?
(b) What property of hydrogen chloride is demonstrated when it is collected by downward delivery (upward displacement)?
(c) Why is hydrogen chloride not collected over water?

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What would happen if (i) Calcium oxide is used to dry hydrogen chloride. (ii) Concentrated hydrochloric acid is kept open. (iii) Hydrogen chloride prepared in laboratory, is passed through water, using a delivery tube.

What would happen if
(i) Calcium oxide is used to dry hydrogen chloride.
(ii) Concentrated hydrochloric acid is kept open.
(iii) Hydrogen chloride prepared in laboratory, is passed through water, using a delivery tube.