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Question
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas and answer the following.
- Name the acid used. Why is this particular acid preferred to other acids?
- Give the balanced equation for the reaction.
- Name the drying agent used in drying hydrogen chloride gas.
- Phosphorous pentoxide and calcium oxide are good drying agents, but they cannot be used to dry hydrogen chloride gas. Why?
- Why is the direct absorption of \[\ce{HCl}\] gas in water not feasible?
- What arrangement is done to dissolve \[\ce{HCl}\] gas in the water?
Solution
The labelled diagram for laboratory preparation of hydrogen chloride is:
a. Concentrated \[\ce{H2SO4}\]. Hydrogen chloride gas, when dissolved in water, forms hydrochloric acid. The gas is highly soluble in water and thus cannot be passed through water with the help of a delivery tube because it leads to back suction, i.e., water may move back into the hot flask through the delivery tube. The delivery tube is connected to a funnel, as shown, and gas is dissolved in water. This prevents the back suction of water.
b. The balanced equation for the reaction:
\[\ce{NaCl + H2SO4 ->[<200°C]NaHSO4 + HCl ^}\]
c. The drying agent used in drying hydrogen chloride gas is conc. Sulphuric acid.
d. Phosphorous pentoxide and calcium oxide are good drying agents, but they cannot be used to dry hydrogen chloride gas because they react with hydrogen chloride.
\[\ce{2P2O5 + 3HCl -> POCl3 + 3HPO3}\]
\[\ce{CaO + 2HCl -> CaCl2 + H2O}\]
e. Hydrogen chloride gas is highly soluble in water. Therefore, it is not collected over water.
f. The funnel arrangement is done to dissolve \[\ce{HCl}\] gas in water.
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RELATED QUESTIONS
Certain blank spaces are left in the following table and these are labelled as A, B, C, D
and E. Identify each of them
| Lab preparation of | Reactants used | Products formed | Drying Agent | Method of collection |
|
| 1 | HCl gas | NaCl + H2SO4 |  |
conc. H2SO4 |  |
| 2 | NH3 gas |
|
Mg(OH)2 NH3 |
 |
 |
The following are pertaining to the laboratory preparation of hydrogen chloride gas.
Write the equation for its preparation mentioning the condition required.
Name the acid used for the preparation of hydrogen chloride gas in the laboratory. Why is this particular acid preferred to other acids?
Write the balanced chemical equation for the laboratory preparation of hydrogen chloride gas.
Explain why when the stopper of a bottle full of hydrogen chloride gas is opened, there are fumes in the air.
The given set up in the figure is for the preparation of an acid.
- Name the acid prepared by this method.
- Name the reactants used.
- Why an empty flask is used?
- What is the drying agent used? Why is this drying agent chosen?
- What is the role of the inverted funnel in the arrangement?
How will you prove that the gas prepared is HCI?
What are the important precautions?
Explain, why (or give reasons for)
Hydrogen chloride is not collected over water.
What is aqua-regia?
Write the equation for :
The preparation of hydrogen chloride from sodium chloride and sulphuric acid. State whether the sulphuric acid should be concentrated or dilute.
Write the equation for:
The reaction between hydrogen chloride and ammonia.
Hydrogen chloride gas, being highly soluble in water, is dried by ______.
One chemical test that would enable you to distinguish between the following pair of chemicals. Describe what happens with each chemical or state 'no visible reaction'.
Sodium chloride solution and sodium nitrate solution.
One chemical test that would enable you to distinguish between the following pair of chemicals. Describe what happens with each chemical or state 'no visible reaction'.
Sodium sulphate solution and sodium chloride solution.
Answer the following question related to the laboratory preparation of the hydrogen chloride gas:
Write the chemical equation.
State a relevant reason for the following:
Hydrogen chloride gas cannot be dried over quick lime.
Identify the gas evolved in the following reaction:
\[\ce{MnO2}\] reacts with concentrated \[\ce{HCl}\].
