IX Practical Chemistry KBSE Experiment No. 10

To Prepare Hydrogen Chloride Gas and study its properties.

Viva Voce
Q.1. Who discovered Hcl Gas?

Ans. It was discovered in 1664 for the first time by Basll Valentine.


Q.2. Who prepared it first?

Ans. Joseph Priestly prepared it in 1772 and collected over Mercury and he called it Marine Acid air. It was prepared from Sea Salt.


Q.3. What is the reaction of Hydrogen and Chlorine?

Ans. If equal volumes of gases are taken and mixed together in bright sunshine then the gases combine together with great explosion.


Q.4. How will you prepare Hydrochloric Acid gas in Science Laboratory?

Ans. It is prepared in the Science Laboratory by the action of sulphuric Acid on Sodium Chloride

NaCl + H2SO4 -------> NaHSO4 + HCl (Low Temperature)

2 NaCl + H2SO4 -----> Na2SO4 + 2HCl (High Temperature)


Q.5. Can you use Nitric Acid (HNO3) or Hydrochloric Acid in place of SUlphuric Acid (H2SO4) for preparing Hcl gas?

Ans. No.


Q.6. Give the name of Apparatus used in this experiment?

Ans.

1. Gas Jar

2. Flask

3. Wire Gauze

4. Tripod Stand

5. Spirit Lamp

6. Delivery Tube

7. Thustle Funnel


Q.7. In what position Thistle Funnel should be placed?

Ans. It should be passed through the hole of the cork vertically and should reach the bottom and he dipped in Acid.


Q.8. Why should the thistle funnel be dipped in Acid?

Ans. In this way there is no escape of HCl gas from the flask


Q.9. At what angle should the delivery tube be placed?

Ans. It should be bent twice at Right Angle.


Q.10. How will you collect this gas?

Ans. It is heavier than air so it is collected by upward displacement of air.


Q.11. Why is it advised to take dry gas jars?

Ans. The Gas is soluble in water.


Q.12 What are the main precautions in this experiment?

Ans.

1. The apparatus should be air tight.

2. The Gas jar should be dry.

3. The thistle funnel should remain dipped into the acid.

4. The gas is collected by upward displacement of air.

5. The Gas jar after they are full should be placed with their mouth upward.


Q.13. What do you understand by Halogens?

Ans. Fluorine, Chlorine, Bromine. Iodine, Astatine together form a remarkable family of element. The whole group is called the Halogen. Halogen means Solt Producer.


Q.14. What are Halides?

Ans. The chlorides, fluorides, Bromides and Iodides are called Halides.


Q.15. What do you understand by Aqua Regia?

Ans. Three parts of conc Hcl and one part of Conc. HNO3 is known as Aqua Regia (Royal Water) because Gold dissolves in it and Arabian Chemist knew it in 8th century.


Q.16. Why do you call tids gas as Hydrogen Chloride?

Ans. The gas is composed of Hydrogen and Chlorine and so it is alos known as Hydrogen Chloride.


Q.17. How do you prepare Hydrochloric Acid from Hydrogen Chloride Gas?

Ans. Hydrochloric Acid Gas is extremely soluble in water so when it is passed through water forms Hydrochloric Acid.


Q.18. What happens when Silver Nitrate solution is treated with Hydrochloric Acid gas dissolved in water?

Ans. A white precipitate of Silver Chloride is formed which is soluble in Ammonium Hydroxide.

AgNO3 + HCl ------> AgCl + HNO3


Q.19. What happen when a glass rod dipped in Ammonium Hydroxide in introduced in the jar of HCl gas?

Ans. White fumes are formed due to formation of Ammonium Chloride.

NH4OH + HCl ------> NH4Cl + H2O


Q.20. What happens when Hydrochloric Acid is treated with Sodium Hydroxide?

Ans. When Hydrochloric Acid is treated with Sodium Hydroxide then Neutralization takes place salt and water are formed.

HCl + NaOH ----> NaCl + H2O


Q.21. What is the colour of HCl gas?

Ans. It is a colourless gas.


Q.22. What is the smell of HCl gas?

Ans. It has pungent irritating smell.


Q.23. What is taste of HCl gas?

Ans. It has an acidic taste.


Q.24. What happens if a burning candle is introduced into HCl gas jar?

Ans. It gets extinguished and the gas does not burn.


Q.25. What is the action of moist blue litmus paper with HCl gas?

Ans. The blue litmus paper turns red indicating that HCl gas is acidic in nature.


Q.26. Is gas lighter or heavier than air?

Ans. The gas is heavier than air.


Q.27. Is the gas soluble in water?

Ans. The gas is soluble is highly soluble in water.


Q.28. What are the used of Hydrochloric Acid Gas?

Ans.

1. Hydrochloric Acid Gas is used in preparing Hydrochloric Acid.

2. Hydrochloric Acid is used in Electroplating.

3. It is used in textile, dye and drug industry.

4. Hydrochloric Acid is widely used as a common reagent.

5. It is also used for manufacture of Chlorine, Bleaching Powder and Aqua Regia.


Q.29. Does this gas support Combustion?

Ans. No, it does not support combustion.


Q.30. State whether the gas is an element or a compound?

Ans. The gas is compound.


Q.31. What substance is obtained if you dissolve HCl gas in water?

Ans. If Hydrochloric Acid gas is obtained in water then Hydrochloric Acid is obtained.


Q.32. What chemicals are required for preparing HCl gas in Science Laboratory?

Ans. Sodium Chloride (NaCl) and Sulphate Acid (H2SO4) are required in the preparation of Hydrogen Chloride gas.


Q.33. Why is the gas not collected in the wet gas jar?

Ans. The gas is not collected in the wet jar because it is soluble in water.


Q.34. By which method Hydrochloric Acid gas is collected?

Ans. It is collected by the upward displacement of air because it is heavier than air.


Q.35. What are the precautions in this experiment?

Ans.

1. All the apparatus should be air tight.

2. It should be prepared in a well ventilated room.

3. Small quantity of Chemicals should be taken in the round bottomed flask.

4. The gas is must be dry.

5. The lower end of the thistle funnel should be kept immensed in the acid.


Q.36. How do you confirm whether the jar is completely filled up with the gas or not?

Ans. If we bring a rod moistened with Ammonium Hydroxide near the mouth of the jar then the white fumes of Ammonium Chloride ar produced which indicates that the jar is full of HCl gas.


Q.37. Why a burning match stick is put off when introduced in the jar of this gas?

Ans. It is due to the reason that gas is not a supporter of combustion.


Q.38. What is the action of Hydrochloric Acid on the metals like Za, Na, K etc.

Ans. It reacts with many metals forming their chlorides and Hydrogen gas is given out.

Zn + 2HCl --------> Zin Cl2 + H2

2K + 2Hcl --------> 2KCl + H2

Q.39. What are the other methods of preparing HCl?

Ans.

1. By the direct combination of Hydrogen and Chlorine.

2. By the action of Chlorine on Hydrogen Compound.


Q.40. What is left behind in the flask after preparation of this gas in Science Laboratory?

Ans. Sodium Sulphate.


Q.41. How will you identify this gas?

Ans. It turns blue litmus red, forms white precipitate with Silver Nitrate.


Q.42. What are Acids?

Ans. Acids are those compounds which are sour in taste, turn blue litmus and give H+ ions in water.


Q.43. How would you prove that HCl gas is highly soluble in water?

Ans. It can be proved by performing fountain experiment.


Q.44. How do you prepare dilute acid from HCl, HNO3 and H2SO4?

Ans. We should never add water to the bottle of concentrated acid because when acid dissolves in water large quantity of heat is produced and it also dissolves violently so the bottle may break. Hence in order to prepare dilute acid we must pour Conc. acid slowly into vessel containing water, but we must never pour water in Conc. acid.


Q.45. Why is it called HCl?

Ans. It is a compound of Hydrogen and Chlorine?


Q46. What substance is obtained when the gas is dissolved in water?

Ans. Hydrochloric Acid is formed.


Q.47. How will you maintain the regular flow of the gas?

Ans. By warming the flask gently towards the end the regular supply of the gas is maintained.


Q.48. Can you collect this gas over water like Hydrogen and Oxygen gas?

Ans. No, it can not be collected because it is highly soluble in water.


Q.49. How will you know with the help of Litmus paper that the jar is of gas?

Ans. If we bring a moist blue litmus paper near the mouth of gas jar, it turns red.


Q.50. How do you prepare HCl on large scale?

Ans. It is generally prepared on large scale by the reaction of common salt and conc. H2SO4.


Q.51. Why is it so that the colour of commercial Hydrochloric Acid is yellow?

Ans. Due to presence of Ferric Chloride (FeCl3) the colour is yellow.


Q.52. How many times it is heavier than Hydrogen?

Ans. It is 18.25 times heavier than Hydrogen.


Q.53. Does it burn in air?

Ans. No it does not burn in air.


Q.54. Can it be liquified?

Ans. Yes, it can be liquified to a colourless liquid.


Q.55. What is Fountain's Experiment?

Ans. Take a dry flask fitted with rubber stopper and a glass tube ending in a flask. Fill the flask completely with HCl gas. Now dip the other end into water containing blue litmus solution. After some time water rushes up in the form of fountain in the flask and its colour changes from blue to red.


Q.56. What is the action of dry HCl gas on dry blue litmus?

Ans. Dry HCl gas has no action on dry blue litmus paper.


Q.57. What happen if the glass cover of HCl gas jar is removed?

Ans. If the glass cover is removed from the mouth of a jar it fumes in contact with moist air.


Q.58. What are the main important tests of HCl gas?

Ans.

1. HCl gas forms with Ammonia white fumes of NH4Cl (Ammonium Chloride).

2. If HCl is passed through test tube containing MnO2 then Chlorine is evolved.

3. Solution of HCl gas in water turns.

4. Gives a white precipitate of AgCl with AgNO3 solution.