Frank Solutions for Chapter 10 Study of Sulphur Compound: Sulphuric Acid Class 10 Chemistry ICSE
1. How does sulphuric acid occur in nature ?
Answer
Sulphuric acid is found in some of the hot springs.
2. Describe the theory of manufacture of sulphuric acid by contact process, with all the necessary conditions
(No technical details are required but equations should be given for each stage of process).
Answer
3. Define the following terms :
(i) Constant boiling mixture
(ii) Hygroscopic substance
(iii) Oleum
(iv) Dehydrating agent
Answer
(i) Constant boiling mixture: Mixture which boils without any change in composition is known as constant boiling mixture.
(ii) Hygroscopic substance: The compound which absorbs water vapour from the atmosphere.
(iii) Oleum: Oleum is called pyrosulphuric acid a orthosulphuric acid. Formula is H2S2O7
(iv) Dehydrating agent: The compound which has mere affinity for water. It removes atoms of hydrogen and oxygen in the form of water from the composition of a substance.
4. Name the fdlowing:
(a) Products obtained by dissolving sulphur dioxide and chlorine in water.
(b) The catalyst used in the contact process.
(c) Soluticn obtained by dissolving sulphur trioxide in 98% sulphuric acid.
(d) Products obtained by treating zinc with dilute sulphunc acid.
(e) Products obtained by treating ferrous sulphide with dilute sulphunc acid.
(f) The precipitate obtained by treating aguecus lead nitrate with dilute sulphuric acid. (g) The precipitate obtained by treating aquecus barium chloride with dilute sulphuric cod.
(h) The precipitate obtained by treating carbon with hot concentrated sulphuric acid. (i) The property used to prepare HCl and HNO3 from H2SO4 .
Answer
(a) Products obtained by dissolving sulphur dioxide and chlorine in water are sulphuric acid and hydrochloric acid. 
(b) Vanadium pentoxide is used as catalyst in contact process.
(c) When SO3 is dissolved in 98% sulphuric acid it forms oleum. 
(d) Zinc is treated with Sulphuric acid it forms Zinc sulphate and hydrogen. 
(e) When ferrous sulphide is treated with sulphuric acid it forms ferrous sulphate and hydrogen sulphide. 
(f) The precipitate of PbSO4 is formed when lead nitrate is treated with dilute sulphuric acid. 
(g) when BaCl2 is treated with sulphuric acid, precipitate of BaSO4 is formed. 
(h) When carbon is treated with hot conc. Sulphuric acid then Water, sulphur dioxide and carbon dioxide are formed. 
(i) The property used to prepare HCl and HNO3 from H2SO4 is that Sulphuric acid is non - volatile acid. So when treated with salts of more volatile acids and heated , concentrated sulphuric acid displaces the more volatile acids.
5. What would you observe in the following cases ?
(i) Sulphur trioxide is dissolved in water on a large scale.
(ii) Concentrated sulphuric acid is added to equal volumes of cold water.
(iii) 100 ml of 98% sulphuric acid is kept open.
(iv) Hot concentrated sulphuric acid is added to sodium chloride crystals.
(v) Dilute sulphuric acid is added to ferrous sulphate solution.
Answer
(i) When water is dissolved in large scale then sulphuric acid is formed. 
(ii) When concentrated sulphuric acid is added to equal volume of cold water it limit down the heat which is released.
(iii) when 100 ml of 98% sulphuric acid is kept in open it absorbs water vapours from atmosphere and its level goes up.
(iv) When hot concentrated sulphuric acid is added to sodium chloride crystals then white dense fumes are seen if a rod dipped in ammonia solution is brought near it.
(v) No visible change is observed.
6. Give reasons for the following:
(i) In the contact process, sulphur dioxide is dissolved in 98% sulphuric acid and not in water.
(ii) When solution of sulphur dioxide is exposed is exposed to ear, it gets converted to sulphuric acid.
(iii) When diluting concentrated sulphuric acid , the acid should be added to water and not water to the acid.
(iv) When concentrated sulphuric acid is exposed to air, its volume increases and it becomes slightly dilute.
(v) Sulphuric acid can form two kinds of salts with sodium chloride.
(vi) When barium chloride is added to dilute sulphuric acid, a white precipitate is formed.
(vii) When carbon is heated with concentrated sulphuric acid, carbon dioxide is formed.
(viii) Ammonia gas cannot be dried by passing through concentrated sulphuric acid.
(ix) When concentrated sulphuric acid is added to sugar/glucose, a black mass is left behind.
(x) Concentrated sulphuric acid should not be added to oxalic acid or formic acid in the open laboratory.
(xi) When concentrated sulphuric acid is added to blue crystalline copper sulphate, it turns powdery white.
(xii) Concentrated sulphuric acid must be stored in airtight bottles.
(xiii) Cotton clothes get burnt with concentrated sulphuric acid.
(xiv) H2SO4 cannot be prepared by heating sodium sulphate with conc. HCl or HNO3
Answer
(i) In contact process sulphur trioxide formed is dissolved in sulphuric acid and not water because sulphur trioxide when directly dissolved in water gives highly exothermic reaction.
(ii) Sulphur dioxide gets oxidized when exposed to air to form sulphur trioxide which reacts with water vapours to form sulphuric acid. 
(iii) When water is added to concentrated sulphuric acid the heat evolved may be sufficient to raise the temperature of water to its boiling point. This may throw acid violently out of the container. Thus concentrated sulphuric acid is diluted by adding a small amount of sulphuric acid to large amount of water.
(iv) When concentrated sulphuric acid is exposed to air, it absorbs water vapours from the atmosphere thus increasing its volume and becoming dilute.
(v) Sulphuric acid when reacts with sodium chloride it forms sodium bisulphate and hydrochloric acid because sulphuric acid when treated with salts of more volatile acids displaces the more volatile acid. 
(vi) When barium chloride is added to dilute sulphuric acid a white precipitate of barium sulphate is 
(vii) Hot concentrated sulphuric add act as a powerful oxidizing agent. Due to heat it decomposes to form nascent oxygen which helps in oxidation of carbon to carbon dioxide. 
(viii) Ammonia gas being basic in nature cannot be dried by using concentrated sulphuric acid.
(ix) The carbohydrates contain carbon, hydrogen and oxygen. The hydrogen end oxygen are always in ratio of 2:1 which is absorbed by acid in the form of water, thus leaving carbon behind This is also called as chafing.
(x) Concentrated sulphuric acid should not be added to oxalic add or formic acid as it removes water and forms Carbon monoxide. Carbon monoxide is harmful far health so this addition must be done in an open laboratory.
(xi) When concentrated sulphuric acid is added to blue crystalline copper sulphate, it removes water from salt and turns it into powdery white.
(xii) Concentrated sulphuric acid must be stored in air tight bottles as it gains water from air and gets slightly diluted thus resulting in increase in volume
(xiii) Cotton contains cellulose. When cotton is treated with concentrated sulphuric acid it removes water from cotton and carbon is left behind .This way cotton clothes get burnt.
(xiv) As sulphuric acid is non volatile, it is used to prepare volatile acids like HCl and HNO3 .Thus these acids cannot be used to prepare sulphuric acid.
7. How are the following oonversicns brought about? Give equations and anditicns:
(i) Sulphur trioxide to sulphur acid.
(ii) Sulphur trioxide to oleum.
(iii) Dilute sulphuric acid to hydrogen.
(iv) Aqueous barium chloride to barium sulphate.
(v) Aqueous lead nitrate to lead sulphate.
(vi) Sodium chloride to hydrogen chloride.
(vii) Sucrose to sugar charcoal.
(viii) Oxalic acid to carbon monoxide.
Answer
(i) Sulphur trioxide to sulphur acid : There is absorption of sulphur trioxide in 98% sulphuric acid to form oleum. 
(ii) Sulphur trioxide to oleum :
Absorption of sulphur trioxide in 98% sulphuric acid to form oleum . 
(iii) Dilute sulphuric acid to hydrogen : Dilute sulphuric acid react with metals above hydrogen in the activity series to form sulphate salts and hydrogen.
(v) Aqueous lead nitrate to lead sulphate : Dilute sulphuric acid when added to the aqueous solution of lead form their insoluble sulphates.
(vi) Sodium chloride to hydrogen chloride : Sulphuric acid when reacts with sodium chloride it forms sodium bisulphate and hydrochloric acid because sulphuric acid when treated with salts of more volatile acids displaces more volatile acids.
(vii) Sucrose to sugar charcoal : Carbohydrates contain carbon, hydron and oxygen. Thus sulphuric acid removes hydrogen and oxygen in form of water leaving behind carbon.
(viii) Oxalic acid to carbon monoxide : Sulphuric acid is used to remove moisture from oxalic acid.
8. Describe the reactions that show
(i) Concentrated sulphuric acid is a non - volatile acid.
(ii) Concentrated sulphuric acid is a dehydrating agent
(iii) concentrated sulphuric acid behaves as oxidizing agent.
(iv) Dilute sulphuric acid behaves as dibasic acid.
Answer
9. Why is sulphuric acid known as king of chemicals and oil vitriol ?
Answer
Sulphuric acid is known as king of chemicals because in almost all industries it is used directly or indirectly. In 8th century it was obtained by distillation of green vitriol (FeSO4.7H20). It is called oil of green vitriol because of its oily appearance and because of the fact that it was present in vitreous or glassy substances like ferrous sulphate etc.
10. Give examples of the use of sulphuric acid as
(i) An electrolyte in everyday use,
(ii) Non - volatile acid,
(iii) An oxidizing agent.
Answer
(i) In manufacturing of fertilizers sulphuric acid act as an electrolyte.
(ii) In chemical industry for the manufacturing of hydrochloric acid & nitric acid it acts as a non - volatile acid.
(iii) In petroleum industry sulphuric acid act as oxidizing agent.
11. (i) How will you distinguish between dilute H2SO4 and conc. H2SO4 ?
(ii) How will you distinguish between conc. HCl and conc. H2SO4 ?
(iii) Give main differences between drying agent and dehydrating agent.
Answer
(i) Difference between dilute H2SO4 and Conc. H2SO4:
|
S. No. |
Dilute sulphuric acid |
Concentrated sulphuric acid |
|
1. |
Barium Chloride test : Barium chloride is added to dilute sulphuric acid white ppt.s of barium sulphate is formed. The precipitate is insoluble in dil. Hydrochloric acid or nitric acid. |
1. Addition to copper : conc. Sulphuric acid is added to Copper and heated. Sulphur dioxide, which is colourless gas with the smell of burnt sulphur is evolved. |
|
2. |
Lead nitrate test : Lead nitrate is added to dil. Sulphuric acid. White ppt. of lead sulphate is formed. The ppt. is insoluble in dil. Hydrochloric acid or nitic acid. |
Addition of common salt : common salt is added to conc. Sulphuric acid. Hydrogen chloride a colourless pugent smelling acidic gas is evolved. Dense white fumes are seen if a rod dipped in ammonia solution is brought near it. |
(ii) Conc. HCl and Conc. H2SO4:
|
Conc. HCl |
Conc. H2SO4 |
|
1. Addition to silver nitrate : |
1. Addition to copper: conc. Sulphuric acid is added to Copper and heated. Sulphur dioxide, which is colourless gas with the smell of burnt sulphur is evolved. Cu + 2H2SO4 → CuSO4 + 2H2O + SO2 |
|
2. A glass rod dipped in conc. HCl is brought in contact with ammonia gas, curdy white fumes of ammonium chloride is seen around the glass rod. |
2. Glucose when conc. Sulphuric acid |
(iii) Difference between Drying agent and dehydrating agent :
|
S. No. |
Drying agent |
Dehydrating agent |
|
1. |
Drying agent removes superficial water sticking to the surface of a given substance. |
Dehydrating agent removes atoms of hydrogen and oxygen in the form of water molecules from the composition of a substance |
|
2. |
Drying agent brings about a physical change. |
Dehydrating agent brings about chemical change. |
|
3. |
No change in the chemical composition of a substance takes place when drying agent is used. |
The dehydrating agent brings about a change in the chemical composition of a substance. |
12. Choose the current answer from the options given below :
(i) In the preparation of H2SO4 by contact process V2O3 is used as a catalyst in the reaction. It is
(a) S + O2→ SO2
(b) SO2 + H2SO4→ H2S2O7
(c) SO3 + H2O → H2SO4
(d) 2SO2 + O2→ 2SO3
(ii) When conc. H2SO4 comes in contact with sugar, it becomes black due to
(a) Hydrolysis
(b) Decolourisation
(c) Dehydration
(d) Hydration
(iii) Which of the following gas dissolves in H2SO4 to give alum?
(a) SO2
(b) H2S
(c) S2O
(d) SO3
(iv) In the contact process, the impurities of arsenic are removed by
(a) Fe2O3
(b) Fe(OH)3
(c) AlCOH3
(d) Cr(OH)3
(v) The catalyst used for the oxidation of SO2 to SO3 in contact process is
(a) Finally divided iron
(b) Molybdenum
(c) Vanadium
(d) Nitric oxide
Answer
(i) 2SO2 + O2→ 2SO3
(ii) Dehydration
(iii) SO3
(iv) Fe(OH)3
(v) Vanadium pentoxide
13. Fill in the blank with appropriate word/words :
(i) The catalyst used in contact process for the manufacture of H2SO4 is ______ or ______.
(ii) For the reaction SO2 + O2⇌ SO3 + Heat, the favourable conditions are ______ and _____.
(iii) Oil of Vitriol is _____
Answer
(i) The catalyst used in contact process for the manufacture of H2SO4 is platinum or Vanadium pentoxide
(ii) For the reaction SO2 + O2⇌ SO3 + Heat, the favorable conditions are high pressure and low temperature
(iii) Oil of vitriol is sulphuric acid.
14. Give reason for the following :
Concentrated sulphuric acid is kept in airtight bottles.
Answer
Concentrated sulphuric acid absorbs water vapours from the atmosphere. Hence it should be kept in air tight bottles.
15. Name the anion [negative ion ] present in the following compound :
Compound D when warmed with dilute H2SO4 gives a gas which turns acidified potassium dichromate solution green.
Answer
Sulphuric acid when treated with sulphites gives sulphate salts, water and sulphur dioxide gas. Sulphur dioxide turns potassium dichromate solution green.
Thus the negative ion is Sulphite ion.
16. The following statement is correct only under certain conditions. Rewrite the statement including the appropriate conditions.
Oxalic acid reacts with sulphuric acid to produce carbon monoxide and carbon dioxide.
Answer
Oxalic acid reacts with sulphuric acid to produce carbon monoxide
17. (i) What is the purpose of the contact process ?
(ii) Name the two gases that are combined during the contact process.
(iii) Name the catalyst used in the process.
(iv) Write the equation for the reaction between zinc and the final product of the contact process.
Answer
(i) The purpose of contact process is to manufacture sulphuric acid.
(ii) Two gases that are combined during contact process are sulphur dioxide and sulphur trioxide.
(iii) Vanadium pentoxide is the catalyst used in the process.
(iv) Zn + H2SO4 → ZnSO4 + H2
18. Name two other acids other than sulphuric acid, which can be prepared by using sulphuric acid.
Answer
Two other acids other than sulphuric acid which can be prepared by using sulphuric acid are hydrochloric acid and nitric acid.
19. In using sulphuric acid to prepare other acids, as mentioned above, which property of sulphuric acid is used ?
Answer
Sulphuric acid is non - volatile. So when it is treated with salts of more volatile acids, and heated, concentrated sulphuric acid displaces the more volatile acids.
20. Sulphuric acid can be used to prepare a number of gases in the laboratory. Write balanced equations for the reactions from which the following gases are obtained, using dilute sulphuric acid as one of the reactants :
(i) Hydrogen
(ii) Carbon dioxide
(iii) Sulphur dioxide
Answer
21. What would you see, when a crystal of CuSO4 . 5H2O is placed in concentrated sulphuric acid? Give reason to explain your observation.
Answer
When crystals of CuSO4 . 5H2O is placed in concentrated sulphuric acid, it removes the water of crystallization of hydrated salt and renders them anhydrous. Its colour change to white .
22. Write balanced equations for the three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the contact process. Name the catalyst used in the contact process.
Answer
23. What do you observe when barium chloride solution is added to dilute sulphuric acid ?
Answer
When barium chloride solution is added to dilute sulphuric acid a white precipitate of barium sulphate is formed. The precipitate is insoluble in dil. Hydrochloric acid. 
24. Write balanced equation for the reaction between iron and dilute sulphuric acid.
Answer
Balanced equation for the reaction between iron and dilute sulphuric acid is : 
25. Name the oxide of sulphur which reacts water to give sulphuric acid.
In the contact process, the direct reaction between oxide of sulphur and water is avoided. In this process what does the oxide of sulphur react with instead of water, and what is the name of the product ?
Answer
26. Write balanced equation for the reaction of dilute sulphuric acid with each of the
following :
(i) Copper carbonate
(ii) Lead nitrate solution
(iii) Zinc hydroxide.
Answer
27. In this question, you required to supply the word (or words) that will make the sentence correct. Rewrite the copper statement. Copper sulphate crystals are dehydrated by sulphuric acid.
Answer
Sulphuric acid removes water of crystallization from Hydrated sulphate.
28. Write balanced chemical equation for the reaction between zinc and dilute sulphuric acid.
(i) What is the purpose of the contact process ?
(ii) Name the catalyst used in the contact process.
(iii) Write the balanced equation for the reaction in the contact process, which takes place in thepresence of catalyst.
Answer
29. What do you see when concentrated sulphuric acid is added to copper sulphate-5-water (You are not required to say what is happing, nor is it necessary to name the products. )
Answer
When concentrated sulphuric acid is added to copper sulphate-5 water its colour change to white.
30. Copy and complete the following table. Column 3 has the names of gases to be prepared using the substance you enter in column 1, along with dilute or concentrated sulphuric acid, as indicated in Column 2.
|
Column 1 |
Column 2 |
Column 3 |
|
Substance reacted with acid |
Dilute or concentrated sulphuric acid |
Gas |
|
|
|
Hydrogen |
|
|
|
Carbon dioxide |
|
|
|
Only chlorine |
Write the equation for the laboratory preparation of :
(i) Sodium sulphate using dilute sulphuric acid.
(ii) Lead sulphate using dilute sulphuric acid.
Answer
Column 1 | Column 2 | Column 3 |
Substance reacted with acid | Dilute or concentrated sulphuric acid | Gas |
Metal | Dilute sulphuric acid | Hydrogen |
Carbonate | Dilute sulphuric acid | Carbon dioxide |
Metal chlorides | Conc. sulphuric acid | Only chlorine |
31. Which concentrated acid oxidizes sulphur directly to sulphuric acid ? Write the equation for the same. What is the name of the porcess by which sulphuric acid is manufactured ? Name the catalyst used in the process.
Answer
Hot concentrated nitric acid oxidizes sulphur directly into sulphuric acid. 
The name of the process by which sulphuric acid is manufactured is contact process.
Vanadium pentoxide is the catalyst used during the process.
32. Complete the following sentence, choosing the correct word from the brackets.
" Concentrated sulphuric acid is used in the laboratory preparation of nitric acid and hydrochloric acid because it is _____ (less volatile/stronger in comparison to these two acids."
Answer
Less volatile.
33. Write the equations for the laboratory preparation of the following salts, using sulphuric acid.
(i) Iron (II) sulphate from iron.
(ii) Copper sulphate from copper.
(iii) Lead sulphate from lead nitrate.
(iv) Sodium sulphate form sodium carbonate.
Answer
34.
(i) Name the catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C.
(ii) In the contact process for the manufacture of sulphuric acid, sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two - step procedure is used. Write the equations for the two steps involved in D.
(iii) What type of substance will liberate sulphur dioxide from sodium sulphite in step E ?
(iv) Write the equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step F ?
Answer
35. Write balanced equation for potassium hydrogen carbonate and dilute sulphuric acid.
Answer
Balanced equation : 
36. A, B, C and D summarize the properties of sulphuric acid depending on whether it is dilute or concentrated. Choose the property (A, B, C or D), depending on which is relevant to each of the preparations (i) to (iii)
A. Dilute add (typical add properties)
B. Non-volatile dead
C. Oxidizing agent
D. Dehydrating agent
(i) Preparation of hydrogen chloride.
(ii) Preparation of ethane from ethanol.
(iii) Preparation of copper sulphate from copper oxide.
Answer
(i) B
(ii) C
(iv) A
37 (a) Name the process used for the large scale manufacture of sulphuric acid.
(b) Which property of sulphuric acid accounts for its use as a dehydrating agent?
(c) Concentrated sulphuric acid is both an oxidizing agent and a non-volatile add. Write one equation each to illustrate the properties of sulphuric acid mentioned above.
Answer
(a) Contact process is used for the large scale manufacture of sulphuric acid.
(b) Sulphuric acid has great affinity for water hence it is used as dehydrating agent.
(c) As an oxidizing agent : 
38. Write the balanced chemical equations for the following conversions :
(a) Lead sulphate from lead nitrate solution and dilute sulphuric acid.
(b) Copper sulphate from copper and concentrated sulphuric acid.
(c) Ammonium sulphate from ammonia and dilute sulphuric acid.
Answer
39. Some properties of sulphuric acid are listed below. Choose the property A, B, C or D which is responsible for the reaction (a) to (e) . Some properties may be repeated.
A. Acid
B. Dehydrating agent
C. Non - volatile acid
D. Oxidizing agent
(a) C12H22O11 + nH2SO4 → 12C + 11H2O + nH2SO4
(b) S + 2H2SO4 → 3SO2 + 2H2O
(c) NaCl + 2H2SO4 → NaHSO4 + HCl
(d) CuO + 2H2SO4 → CuSO4 + H2O
(e) Na2CO3 + 2H2SO4 → Na2SO4 + H2O + CO2
Answer
(a) B
(b) D
(c) C
(d) A
(e) A
40. (a) HCl, HNO3 and H2SO4 are formula or three compounds. Which of these compounds has the highest boiling point and which has the lowest ?
(b) Dilute hydrochloric acid and dilute sulphuric acid are both colourless solutions. How will the addition of barium chloride solution to each help to distinguish between the two ?
Answer
(a) HCl has higher boiling point where as sulphuric acid has lower boiling point.
(b) When barium chloride is added to dilute sulphuric acid, white precipitate of barium sulphate is formed but with dilute hydrochloric acid no change is observed.
45. Choose the correct answer :
Dilute sulphuric acid will produce a white precipitate when added to a solution of :
(a) Copper nitrate
(b) Zinc nitrate
(c) Lead nitrate
(d) Sodium nitrate
Answer
Lead nitrate
46. Making use only of substances chosen from those given below :
Dilute sulphuric acid, Sodium carbonate, Zinc, Sodium sulphite, Lead, Salcium carbonate
Give the equations for the reactions by which you could obtain :
(i) Hydrogen
(ii) Sulphur dioxide
(iii) Carbon dioxide
(iv) Zinc carbonate (two steps required).
Answer
48. Name the gas evolved in following case :
The gas produced by the action of concentrated sulphuric acid on sodium chloride.
Answer
Hydrogen chloride is a colourless pungent acidic gas produced by the action of concentrated sulphuric acid on sodium chloride.
49. Write the equation for each of the following reactions :
(i) Sulphur is heated with concentrated sulphuric acid
(ii) Concentrated sulphuric acid is poured over sugar
Answer
(i) S + H2SO4→ 3SO2 + 2H2O
50. State your observation for the following cases :
(i) Moist blue litmus is introduced into a gas jar of sulphur dioxide
(ii) Dry red rose petals are placed in the jar of sulphur dioxide
(iii) Paper soaked in potassium permanganate solution is introduced into a gas jar of sulphur diaoxide.
Answer
(i) Litmus turns blue to red, and then gets bleached.
(ii) Dry SO2 has no effect on dry red rose petals.
(iii) Paper turns from pink to white.
51.What would you observe in the following case : Sugar crystals are added to hard glass test tube containing concentrated sulphuric acid.
Answer
Charring of sugar takes place. Sulphuric acid dehydrates sugar leaving behind carbon which is black.
52. (i) With the help of equations, give an outline for the manufacture of sulphuric acid by the contact process
(ii) What property of sulphuric acid is shown by the reaction of concentrated sulphuric acid when heated with
(i) Potassium nitrate
(ii) carbon
Answer
53. In the given equation identify the role played by concentrated sulphuric acid
S + 2H2SO4 → 3SO2 + 2H2O
(a) Non-volatile acid
(b) Oxidising agent
(c) Dehydrating agent
(d) None of the above
Answer
(b) Oxidising agent
54. State one appropriate observation for each of the following.
(i) Concentrated sulphuric acid is added dropwise to a crystal of hydrated copper sulphate.(ii) Dehydration of Concentrated Sulphuric acid with sugar crystals
Answer
(i) When conc. H2SO4 is added to a crystal of hydrated copper sulphate, it removes water of crystallisation from salt.
(ii) C12H22O11 + conc. H2SO4 → 6C + 6H2O
55. Give one equation each to show the following properties of sulphuric acid :
(i) Dehydrating property
(ii) Acidic nature
(iii) As a non-volatile acid
Answer
(i) Dehydrating property of sulphuric acid:
H2SO4 has a great affinity for water, and therefore, it acts as a dehydrating agent.
(ii) Acidic nature of sulphuric acid:
It acts as a strong dibasic acid.
It reacts with metals, metal oxides, metal hydroxides and carbonates to form metallic sulphates and hydrogen at ordinary temperature.
- Mg + H2SO4→ MgSO4 + H2↑
- CuO + H2SO4 → CuSO4 + H2O
- 2NaOH + H2SO4→ Na2SO4 + 2H2O
- ZnCO3 + H2SO4→ ZnSO4 + H2O + CO2↑
(iii) As a non-volatile acid:
It has a high boiling point, so it is used to prepare volatile acids such as HCl, HNO3 and acetic acid from their salts.
NaCl + H2SO4→ NaHSO4 + HCl
NaNO3 + H2SO4 → NaHSO4 + HNO3
CH3COONa + H2SO4 → NaHSO4 + CH3COOH
56. (i) Give balanced chemical equations for the action of sulphuric acid on each of the following
1. Potassium hydrogen carbonate
2. Sulphur
(ii) In the contact process for the manufacture of sulphuric acid give the equations for the conversion of sulphur trioxide to sulphuric acid.
Answer
(i) 1. Action of sulphuric acid on potassium hydrogen carbonate
2KHCO3 + H2SO4→ K2SO4 + 2H2O + 2CO2↑
2. Action of sulphuric acid on sulphur
S + 2H2SO4→ 3SO2 + 2H2O
(ii) In the contact process for the manufacture of sulphuric acid, the equations for the conversion of sulphur trioxide to sulphuric acid are
SO3 + H2SO4→ H2S2O7
(oleum or pyrosulphuric acid)
H2S2O7 + H2O → 2H2SO4
57. A,B,C and D summarise the properties of sulphuric acid depending on whether it is dilute or concentrated.
A = Typical acid property
B = Non-Volatile acid
C = Oxidising agent
D = Dehydrating agent
Choose the property (A,B,C or D) depending on which is relevant to each of the following :
(i) Preparation of hydrogen chloride gas
(ii) Preparation of copper sulphate from copper oxide
(iii) Action of cone, sulphuric acid on sulphur
Answer
(i) B
(ii) A
(iii) C
58. Write balanced chemical equations to show :
(i) The oxidizing action of conc. sulphuric acid on carbon
(ii) The behavior of H2SO4 as an acid when it reacts with magnesium
(iii) The dehydrating property of conc. sulphuric acid
Answer
