Chapter 8.4 – Inorganic Chemistry

Book Name	: Madhyamik Physical Science And Environment
Subject	: Physical Science
Class	: 10 (Madhyamik)
Publisher	: Oriental Book Company Pvt. Ltd
Chapter Name	: Physical and Chemical Properties of Matter

In-text Questions

Question 8.4.1.1

What happens when ammonium sulphate is heated with caustic soda?

Answer

When ammonium sulfate (NH₄)2SO₄ is heated with caustic soda (sodium hydroxide, NaOH), a chemical reaction occurs, leading to the formation of ammonia gas (NH₃), water (H₂O), and sodium sulfate (Na₂SO₄). The reaction can be represented as follows:

(NH₄)₂SO₄ + 2NaOH → 2 NH₃ + 2 H₂O + Na₂SO₄

Question 8.4.1.2  

Why CaO is used for drying NH₃ but not conc. H₂SO₄? 

Answer

CaO reacts with NH₃ to form calcium hydroxide [Ca(OH)₂] and ammonium nitrate [NH₄NO₃]. This reaction removes the moisture content from NH₃ and makes it dry. In contrast, when conc. H₂SO₄ is added to NH₃, it reacts with it to form ammonium sulfate [(NH₄)₂SO₄], which is a salt and does not remove moisture content.

Question 8.4.1.3

How will you get nitric oxide from ammonia? 

Answer

Ammonia is oxidized by air in the presence of a catalyst such as platinum or rhodium at a temperature of about 850-1000°C to produce nitrogen and water:

4NH₃ + 5O₂ → 4NO + 6H₂O

Question 8.4.1.4

What are the colours of Fe(OH)₃ and Al(OH)₃ ? 

Answer

The colour of Fe(OH)₃ is reddish-brown, while the colour of Al(OH)₃ is white.

Question 8.4.1.5

During accidental Leakage of ammonia, the face and eyes should be covered with wet towels, why?

Answer

In case of accidental leakage of ammonia, covering the face and eyes with wet towels can help to reduce the harmful effects of ammonia gas.

Question 8.4.1.6

What is the source of N₂ and H₂ required for the manufacture of ammonia by Haber’s process? 

Answer

Source of N₂: The raw material N₂ is obtained by fractional distillation of liquid air.

Source of H₂: H₂ is obtained from water gas.

Question 8.4.1.7

Mention the catalysts used in Haber’s process. 

Answer

Iron powder

Question 8.4.1.8

Write the conditions of manufacture of urea.

Answer

Conditions of manufacture of urea

1. The process is carried out at a high temperature of around 170-190°C.
2. A high pressure of around 100-200 atm is maintained in the reactor.
3. A catalyst, typically iron oxide, is used to promote the reaction between ammonia and carbon dioxide.
4. The molar ratio of ammonia to carbon dioxide should be maintained at 3:1.

Question 8.4.2.1

What are the reagents needed to prepare H₂S in the laboratory? 

Answer

In the laboratory, H2S can be prepared by reacting a metal sulfide with an acid. The reagents needed are:

1. Metal sulfide: The most commonly used metal sulfide is ferrous sulfide (FeS), although other metal sulfides such as zinc sulfide (ZnS) or copper sulfide (CuS) can also be used.
2. Acid: Hydrochloric acid (HCl) or dilute sulfuric acid (H₂SO₄) can be used to react with the metal sulfide.

Question 8.4.2.2

Name some gases which be prepared in Kipp’s apparatus? 

Answer

Some gases which can be prepared in Kipp’s apparatus are:

1. Hydrogen sulfide (H₂S)
2. Carbon dioxide (CO₂)
3. Chlorine (Cl₂)
4. Sulfur dioxide (SO₂)

Question 8.4.2.3

Mention two physical properties of H₂S.

Answer

Two physical properties of H₂S are:

1. H₂S is a colourless gas with a characteristic odour of rotten eggs.
2. It is denser than air and is soluble in water.

Question 8.4.2.4

How will you prove that H₂S is acidic? 

Answer

To prove that H₂S is acidic, we can perform the following experiment:

1. Take a small amount of H2S gas in a test tube.
2. Add a few drops of blue litmus solution to the test tube.
3. If the H₂S gas is acidic, it will react with the blue litmus solution and turn it red.

Question 8.4.2.5

What happens when H₂S is passed into an acidified potassium dichromate solution? 

Answer

When H2_S is passed into an acidified potassium dichromate (K₂Cr₂O₇) solution, it is oxidized to sulfuric acid (H₂SO₄) and elemental sulfur (S) is formed.

3H₂S (g) + K₂Cr₂O₇ (aq) + 4H₂SO₄ (aq) → 3S ↓ (s) + Cr₂(SO₄)₃ (aq) + K₂SO₄ (aq) + 7H₂O (l)

Question 8.4.2.6

What happens when H₂S is passed into AgNO₃ solution? 

Answer

When H₂S is passed into AgNO₃ solution, a white precipitate of Ag₂S (silver sulfide) is formed according to the following chemical equation:

2AgNO₃ (aq) + H₂S (g) → Ag₂S↓ (s) + 2HNO₃ (aq)

The white precipitate of Ag₂S is insoluble in water and can be used as a confirmatory test for the presence of H₂S in a given sample.

Question 8.4.2.7

Mention the toxic effect of H₂S.

Answer

H₂S (Hydrogen sulfide) is a toxic gas that can cause various harmful effects on human health. Some of the toxic effects of H₂S are:

1. Irritation: H₂S gas can cause irritation to the eyes, nose, and throat, leading to inflammation and pain.
2. Respiratory problems: Inhaling high concentrations of H₂S can cause respiratory problems such as shortness of breath, coughing, and wheezing.

Question 8.4.3.1

Nitrogen is not prepared in the laboratory by heating ammonium nitrite directly give reason.

Answer

Nitrogen is not prepared in the laboratory by heating ammonium nitrite directly because it undergoes decomposition in an explosive manner, releasing nitrogen gas along with water vapour and nitrogen oxide gases, which are toxic and can cause harm to human health.

Question 8.4.3.2

Mention two uses of nitrogen. 

Answer

Two uses of nitrogen are:

1. Nitrogen is used in the manufacturing of ammonia, which is further used in the production of fertilizers.
2. Nitrogen is used in the food industry as a method of preservation.

Question 8.4.3.3

What happens when nitrogen is heated at high temperatures with oxygen?

Answer

Nitrogen and oxygen react at high temperatures at 3000^oC produced by an electric spark to give nitric oxide.

N₂ + O₂ = 2 NO – Heat

Question 8.4.3.4

 Why nitrogen does not react easily.

Answer

Nitrogen is a very stable molecule due to the strong triple covalent bond between the two nitrogen atoms. This bond requires a large amount of energy to break, making nitrogen a very unreactive element under normal conditions.

Question 8.4.3.5

Why does rainwater during thunderstorms contain traces of HNO₃? 

Answer

Rainwater during thunderstorms contains traces of HNO3 due to the formation of nitrogen oxides (NO_x) in the atmosphere by the high-energy electrical discharge of lightning. These NOx species then react with water vapour in the atmosphere to form nitric acid (HNO3), which can dissolve in rainwater and fall to the ground as acidic rain.

Question 8.4.3.6

What is nitrolim? Mention its use.

Answer

The black mixture of calcium cyanamide and carbon is commercially known as nitrolim.

Preparation: When calcium carbide is heated in nitrogen at about 1000°C (1273 K), calcium cyanamide is produced with the separation of carbon.

CaC₂ + N₂ = CaCN₂ + C

Uses: It is largely used as fertilizer.

Question 8.4.4.1

What is the physical state of hydrogen chloride? 

Answer

Hydrogen chloride (HCl) is a gas at room temperature and standard pressure. However, it can be dissolved in water to form hydrochloric acid, which is a liquid.

Question 8.4.4.2

How hydrochloric acid is obtained from NaCl? 

Answer

The NaCl is reacted with sulfuric acid (H₂SO₄) at a temperature of about 500°C and a pressure of about 2 atm. This produces sodium sulfate (Na₂SO₄) and hydrogen chloride (HCl) gas.

2NaCl (s) + H₂SO₄ (l) → Na₂SO₄ (s) + 2HCl (g)

Question 8.4.4.3

Mention the use of Na₂SO₄. 

Answer

The sodium sulphate (Na₂SO₄) is used as a fining agent in the glass manufacturing process, helping to remove small air bubbles and other impurities from molten glass.

Question 8.4.4.4

How is hydrogen chloride manufactured from its elements? 

Answer

At present HCl is manufactured from H₂ and Cl₂ is obtained as a byproduct in the manufacture of NaOH by the electrolytic process. An equal volume is heated in an electric chamber.

H₂ (g) + Cl₂ (g) = 2HCl (g)

The resultant HCl vapour passes out of the acid chamber through an outlet and is cooled by passing through a cooling coil cooled by water. This cooled gas is absorbed in a tower by a shower of water to get a saturated solution of HCl in the water.

Question 8.4.4.5

Give equation and condition the manufacture HCl from Cl₂ and H₂O. 

Answer

Hydrochloric acid can also be manufactured by passing a mixture of Cl₂ and hot water through activated charcoal.

2Cl₂ + 2H₂O = 4HCl + O₂

HCl vapour is absorbed in water and O₂ is passed out.

Question 8.4.4.6

The raw materials H₂ and Cl₂ required to manufacture HCl are obtained as by-products of which industry. 

Answer

The raw materials hydrogen gas (H₂) and chlorine gas (Cl₂) required to manufacture hydrochloric acid (HCl) are typically obtained as by-products of the chemical industry, especially from the production of chlorine-containing compounds.

Question 8.4.4.7

What is the source of SO₂ in the contact process of the manufacture of H₂SO₄? 

Answer

At present HCl is manufactured from H₂ and Cl₂ is obtained as a byproduct in the manufacture of NaOH by the electrolytic process.

Question 8.4.4.8

Name the catalyst used in the conversion of SO₂ to SO₃. 

Answer

The catalyst used in the conversion of SO₂ to SO₃ is vanadium pentoxide (V₂O₅).

Question 8.4.4.9

What is pyrosulphuric acid? 

Answer

Pyrosulfuric acid, also known as oleum or fuming sulfuric acid, is a highly concentrated form of sulfuric acid (H₂SO₄) that contains excess sulfur trioxide (SO₃). Its chemical formula is H₂S₂O₇.

Question 8.4.4.10

Why SO₃ is dissolved in 98% H₂SO₄ and not in water?

Answer

SO₃ is highly reactive and exothermic when it comes in contact with water. When SO₃ is added to water, it can produce a highly corrosive mist of sulfuric acid that can cause damage to the equipment and the environment.

Multiple Choice Questions (MCQ)

Question 1

Ammonia can be obtained by heating ammonium sulphate with –

1. КОН
2. NaCI
3. CaCl₂
4. ZnSO₄

Answer

CaCl₂

Explanation:

Ammonia can be obtained by heating ammonium sulphate with CaCl₂.

Question 2

Ammonia is collected by –

1. downward displacement of water 
2. downward displacement of air
3. upward displacement of air
4. By downward displacement of hot water

Answer

(c) Upward displacement of air

Explanation:

Ammonia is collected by the upward displacement of air.

Question 3

Ammonia is –

1. basic
2. acidic
3. neutral 
4. Insoluble in water

Answer

(a) basic

Explanation:

Ammonia is a basic compound. When it is dissolved in water, it reacts with water to form ammonium hydroxide, which is a strong base. The chemical equation for this reaction is:

NH₃ + H₂O → NH₄OH

Question 4

Ammonium nitrate and Ca(OH)₂ on heating produce –

1. N₂
2. NO₂
3. NH₃
4. NO

Answer

(c) NH₃

Explanation:

Ammonium nitrate and Ca(OH)2 on heating produce NH3 (ammonia). The chemical equation for this reaction is:

Ca(OH)₂ + 2NH₄NO₃ → Ca(NO₃)₂ + 2H₂O + 2NH₃

Question 5

Liquid ammonia contains –

1. 35% NH₃
2. 60% NH₃
3. 80% NH₃
4. 0.0% NH₃

Answer

(d) 0.0% NH₃

Explanation:

Liquid ammonia contains only NH3 molecules and no other substances. Therefore, the percentage of NH₃ in liquid ammonia is 100%, and the other options (35%, 60%, and 80%) are incorrect.

Fill up the blanks

Question

1. The odour of H₂S is like that of ____.
2. Ammonia is ____ soluble in water.
3. Ammonia is prepared by heating ammonium salt and ____.
4. H₂S reacts with ____ to give salt.
5. H₂S reacts with AgNO₃ solution to give ____ precipitate.

Select the correct word from the words in brackets to complete each sentence.

1. SO₂ is converted to SO₃ in the presence of ____ catalyst. (Pt / Ni) 
2. The solid catalysts in a reaction are used in powder form to get ____ surface area. (greater / smaller). 
3. HNO₃ is manufactured from NH₃ by ____ process. (Haber / Ostwald). 
4. The rainwater during thunderstorms is ____ (acidic/basic). 
5. On heating CaC₂ and N₂ at 1000°C produce ____ coloured substance. (Black /white)

Match the Column-1 with Column-2

Answer

Indicate whether the following statements are true or false

Question

1. Nitrogen is prepared in the laboratory by heating ammonium nitrite. 
2. Ammonia is highly soluble in water. 
3. Liquid ammonia contains no water. 
4. Liquid ammonia and liquor ammonia are the same things. 
5. Ammonia has no reducing properties.

Answer

Answer the following questions

Question 1

Write a balanced equation for the preparation of ammonia from NH₄Cl. 

Answer

Balanced equation:

NH₄Cl + NaOH → NH₃ + NaCl + H₂O

Question 2

Ammonia can be liquified at what temperature and pressure? 

Answer

Ammonia can be liquified at a temperature of -33.34°C and pressure of 8.5 atm.

Question 3

Write an equation to show the reducing property of ammonia. 

Answer

Equation showing reducing property of ammonia: 4NH₃ + 3O₂ → 2N₂ + 6H₂O.

Question 4

Write an equation where two gases react to give a solid. 

Answer

Ammonia gas and Hydrogen chloride gas react to form the salt ammonium chloride

NH₃ (g) + HCl (g) → NH₄Cl (s)

Question 5

How will you identify ammonia with Nessler’s reagent?

Answer

Ammonia can be identified with Nessler’s reagent by the formation of a brown precipitate of a complex between ammonia and mercury ions.

Short Answer Type Questions

Question 1

How hydrogen chloride is prepared from Cl₂? 

Answer

Hydrogen chloride (HCl) can be prepared from chlorine gas (Cl2) through a process known as the “direct combination” or “synthesis” method. Here’s the chemical equation for the reaction:

Cl₂(g) + H₂(g) → 2HCl(g)

Question 2

Mention conditions to convert SO₂ to SO₃. 

Answer

SO₂ can be converted to SO₃ in the presence of a vanadium(V) oxide catalyst at a temperature of around 450-500°C and a pressure of around 1-2 atm.

Question 3

How NH₃ is converted to NO. 

Answer

NH₃ is converted to NO by the oxidation process in the presence of a platinum-rhodium catalyst and a temperature range of 800-900°C.

Question 4

Why strong bases like KOH should not be used to prepare ammonia from ammonium salts? 

Answer

Strong bases like KOH should not be used to prepare ammonia from ammonium salts because they can react with NH₄⁺ ions to form NH3 gas, which can escape from the solution and lead to low yields of ammonia.

Question 5

What is liquor ammonia? 

Answer

Liquor ammonia is a concentrated aqueous solution of ammonia containing about 25% to 30% by weight of NH₃. It is also known as aqueous ammonia or ammonia water.

Question 6

Give an example of reducing the property of ammonia. 

Answer

An example of the reducing property of ammonia is its reaction with hot copper oxide to form nitrogen gas and water vapour.

CuO + 2NH₃ → N₂ + 3H₂O + Cu

Question 7

What happens when excess ammonia solution is added gradually to an aqueous solution of CuSO₄? 

Answer

When excess ammonia solution is added gradually to an aqueous solution of CuSO4, a deep blue complex known as cuproammonium sulphate is formed.

CuSO₄ +  NH₄(OH) → [Cu(NH₃)₄SO₄]

Question 8

What happens when ammonium hydroxide is added to an aqueous solution of aluminium chloride?

Answer

When ammonium hydroxide is added to an aqueous solution of aluminium chloride, a white gelatinous precipitate of aluminium hydroxide is formed. The chemical equation for the reaction is:

AlCl₃ + 3NH₄OH → Al(OH)₃ + 3NH₄Cl

Question 9

What is Nessler’s reagent? Mention its use. 

Answer

Nessler’s reagent is the alkaline solution of potassium mercuric Iodide (K2[HgI₄]).

Its main use is to detect and quantify the presence of ammonia and ammonium ions in a solution, as it forms a brown precipitate of a complex between ammonia and mercury ions.

Question 10

Mention the uses of ammonia.

Answer

Uses of ammonia are:

1. Ammonia is widely used in the production of fertilizers as a source of nitrogen.
2. It is used as a refrigerant in industrial refrigeration systems.
3. Ammonia is used in the production of various chemicals, such as explosives, plastics, and pharmaceuticals.

Long Answer (LA) type Questions

Question 1

Write the principle of the manufacture of ammonia.

Answer

The principle of the manufacture of ammonia is based on the reaction between nitrogen and hydrogen gases in the presence of a catalyst, which produces ammonia. The reaction is exothermic and occurs at high temperatures and pressure. The catalyst used in this reaction is typically a mixture of iron oxide and alumina. The process of manufacturing ammonia is known as the Haber process.

Question 2

What is the difference between liquor and liquid ammonia? 

Answer

Liquor Ammonia	Liquid Ammonia
Solution of ammonia gas in water	Pure form of ammonia
Contains impurities like other gases and minerals	Free from impurities
Used in cleaning agents, fertilizers, and other industrial applications	Used as a refrigerant and in the production of pharmaceuticals and plastics

Question 3

What precautions should be taken to combat accidental leakage of ammonia? 

Answer

If there is an accidental leakage of ammonia, the following precautions should be taken:

1. All personnel should immediately evacuate the area to prevent inhalation of ammonia gas, which can be harmful to health.
2.  Open all windows and doors to allow fresh air to enter the area and disperse the ammonia gas.
3. Wear protective gear such as gloves, goggles, and a mask.

Question 4

Describe the principle of large-scale preparation of ammonia. 

Answer

1. The Haber-Bosch process is the most common method for the large-scale preparation of ammonia.
2. This process involves reacting nitrogen gas and hydrogen gas at high temperatures (around 450°C) and pressures (around 200-300 atmospheres) in the presence of an iron-based catalyst.
3. Nitrogen is obtained from the air through a process called fractional distillation, while hydrogen is obtained from natural gas or other sources through a process called steam reforming.
4. The reactants are compressed and fed into a reactor where they are heated and passed over the catalyst.
5. The reaction produces ammonia gas, which is cooled and liquefied for storage and transport.

Question 5

How urea is manufactured? 

Answer

In an autoclave ammonia and carbon dioxide are taken in 3:1 molar proportion, the mixture is heated to 170^oC – 190^oC at a pressure of 100 – 200 atmosphere to give ammonium carbamate (NH₄COONH₂) on reducing pressure this compound gives up water to produce urea.

2NH₃ + CO₂ → NH₄COONH₂ + Heat

NH₄COONH₂ → NH₂CONH₂ + H₂O + Heat

Question 6

Give the principle to prepare H₂S. Mention its reaction with an aqueous solution of CuSO_4.

Answer

In the laboratory, H₂S is prepared by the action of dilute sulphuric acid with ferrous sulphide at room temperature.

Equation : FeS + H₂SO₄ → FeSO₄ + H₂S

When hydrogen sulfide (H₂S) reacts with an aqueous solution of CuSO₄ (copper sulfate), it forms a precipitate of CuS (copper sulfide) and sulfuric acid (H₂SO₄) is also produced as a by-product. The balanced chemical equation for this reaction is:

H₂S (g) + CuSO₄ (aq) → CuS (s)↓ + H₂SO₄ (aq)

Question 7

Mention the principle of Kipp’s apparatus to prepare gas. 

Answer

The Kipp’s apparatus is a laboratory apparatus used to prepare gases by the reaction of a solid with a liquid. It consists of three interconnected glass bulbs arranged vertically, with the solid in the middle bulb. The upper and lower bulbs are connected by a tube and contain the liquid. The middle bulb has a tube with a tap for drawing off gas.

The principle of the Kipp’s apparatus is as follows:

• The liquid is poured into the upper bulb.
• The solid is placed in the middle bulb.
• The tap is closed.
• The pressure of the gas in the middle bulb forces the liquid down into the lower bulb.
• The solid and liquid react to form gas.
• The gas accumulates in the middle bulb.
• The tap is opened and the gas is drawn off.

Question 8

Write with equation the following properties of H₂S.(i) acidic (ii) reducing and (iii) Precipitation. 

Answer

(i) H₂S is acidic and reacts with metal hydroxides to form corresponding sulfides and water. For example, with sodium hydroxide:

H₂S (g) + 2 NaOH (aq) → Na₂S (aq) + 2H₂O (l)

(ii) H₂S is a reducing agent and can reduce metal ions to their elemental forms. For example, with silver nitrate:

H₂S (g) + 2AgNO₃ (aq) → 2Ag (s) + 2HNO₃ (aq) + S (s)

(iii) H₂S can form insoluble metal sulfides when reacted with metal ions in aqueous solutions. For example, with lead (II) nitrate:

H₂S (g) + Pb(NO₃)₂ (aq) → PbS (s) + 2HNO₃ (aq)

Question 9

What is nitrolim? Mention its preparation and uses. 

Answer

The  black mixture of calcium cyanamide and carbon is commercially known as nitrolim.

Preparation: When calcium carbide is heated in nitrogen at about 1000°C (1273 K), calcium cyanamide is produced with the separation of carbon.

CaC₂ + N₂ = CaCN₂ + C

Uses: It is largely used as fertilizer.

Question 10

Write notes about the fixation of aerial nitrogen. 

Answer

Nitrogen fixation is the process of converting atmospheric nitrogen into usable forms for plants and organisms. Certain bacteria can take in atmospheric nitrogen and convert it into ammonia. Aerial nitrogen fixation occurs when bacteria live on the surfaces of leaves, taking in nitrogen and fixing it into a form that can be used by the plant. This process is important in areas with poor soil. Legumes and other plants can host nitrogen-fixing bacteria.

Question 11

Write the principle of the manufacture of H₂SO₄. 

Answer

The principle of the manufacture of H₂SO₄ by the Contact Process involves the following steps:

1. Preparation of sulfur dioxide (SO₂) by burning sulfur or by roasting metal sulfides.
   S + O₂ = SO₂ (4FeS₂ + 11O₂ = 2Fe₂O₃ + 8SO₂)
2. Conversion of SO₂ to sulfur trioxide (SO₃) by catalytic oxidation with oxygen using a vanadium pentoxide catalyst at a temperature of around 450-500°C.
   2SO₂ + O₂ = 2SO₃ + Heat
3. Absorption of SO₃ in 98% sulfuric acid to produce oleum (a mixture of H₂SO₄ and SO₃).
   H₂SO₄ + SO₃ = H₂S₂O₇
4. Dilution of oleum with water to obtain the desired concentration of sulfuric acid (typically 98% or 96%).
   H₂S₂O₇ + H₂O = 2H₂SO₄
5. Recycling of unreacted SO₂ and excess oxygen to the oxidation step.

Question 12

How HNO₃ is manufactured by Ostwald’s process? 

Answer

HNO₃ is manufactured by Ostwald’s Process, which involves the following steps:

1. Ammonia (NH₃) is oxidized to nitrogen monoxide (NO) by heating it in the presence of a platinum-rhodium catalyst at a temperature of around 850-900°C.
   4NH₃ (g) + 5O₂ (g) → 4NO (g) + 6H₂O (g)

2. The nitrogen monoxide is then oxidized to nitrogen dioxide (NO2) by reacting it with excess oxygen in the presence of a platinum-rhodium catalyst at a temperature of around 450-550°C.
   2NO (g) + O₂ (g) → 2NO₂ (g)

3. The nitrogen dioxide is then absorbed in water to form nitric acid (HNO₃), which is then concentrated to the desired strength through distillation.
   3NO₂ (g) + H₂O (l) → 2HNO₃ (aq) + NO (g)

Question 13

How HCl is prepared on a large scale from NaCl? 

Answer

An early process to manufacture hydrochloric acid by distilling a mixture of Nacl and concentration H₂SO₄ at 500^oC in a cast iron vessel, provided with delivery tubes. The evolved HCl vapour is absorbed in a series of glazed earthen receivers containing water. This acid contaminated with carried-over H₂SO₄ is removed by distilling over a mixture of BaCl₂ and copper turnings.

2NaCl (s) + H₂SO₄ (l) → Na₂SO₄ (s) + 2HCl (g)

Question 14

Why the manufacture of H₂SO₄ from SO₃ in the presence of a catalyst is called a contact process? Why catalysts are taken in powdered form?

Answer

The manufacture of H₂SO₄ from SO₃ in the presence of a catalyst is called a contact process because the reaction between SO₂ and O₂ takes place on the surface of a catalyst, and the reactants make only brief contact with the catalyst. This process occurs in a series of chambers or containers, and the gases “contact” the catalyst on their way through each chamber.

Catalysts are taken in powdered form to maximize their surface area and increase the number of active sites available for the reaction to occur.

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