10th Class Chemistry Chapter 10  Acids bases and salts

10th Class Chemistry Chapter 10  Acids bases and salts

Question 1: In how many groups all present day organic and inorganic substances are classified? Also write a note on history of acids?

Answer: History of Acids and Bases:

Acids, bases and salts are three distinct classes in which almost all the organic and inorganic compounds are classified. A famous Muslim Chemist Jabir Bin Hayan prepared nitric acid (HNO3 ), hydrochloric acid (HCl) and sulphuric acid (H2SO4 ). In 1787, Lavoisier named binary compounds of oxygen such as CO2and SO2 as acids which on dissolution in water gave acidic solutions. Later on in 1815, Sir Humphrey Davy discovered that there are certain acids which are without oxygen, e.g., HCl. Davy proved the presence of hydrogen as the main constituent of all acids. It was also discovered that all water soluble metallic oxides turn red litmus blue, which is a characteristics of bases.

The word acid is derived from the Latin word ‘Acidus’ meaning sour. The first acid known to man was acetic acid, i.e., in the form of vinegar.

We all have a little concentration of hydrochloric acid in our stomach, which helps to break down the food. Sometimes, the amount of stomach acid becomes too much, which causes ‘acidity’. This uncomfortable feeling is easily treated by taking an alklaline medicine. The alkali neutralizes the acid, producing a harmless chemical called a salt.

 

 

Question 2: What are the characteristics properties through which acids and bases can be differentiated from each other?

 

Answer: Acids and bases shows characteristics properties. Some of them are as follows:

 

Table : Acids and Bases are recognized by their characteristic properties, such as :

1. Acids have sour taste. For example, unripe citrus fruits or
lemon juice.2. They turn blue litmus red.3. They are corrosive in concentrated form.4. Their aqueous solutions conduct electric current.
1. Bases have bitter taste and feel slippery, for example, soap is
slippery to touch.2. They turn red litmus blue.3. They are non-corrosive except concentrated forms of NaOHand KOH.

4. Their aqueous solutions conduct electric current.“

5. Smell of onion remains in an acid. 5. Smell of onion diminishes in a base.
6. Odour or smell of vanilla essence remains when it is added to an acid. 6. Odour of vanilla essence disappears when it is added to a base.
7. Colour of turmeric remains yellow. 8. Colour of turmeric turns into red from yellow.
8. Penolaphthaline remains colourless in acids. 8. Phenolaphthaline turns pink in bases.
9. Methyl Orange turns pink in acids.

10. Those compounds which provide hydrogen ion (h+) in aqueous solutions are called acids.

11. An acid is a substance which produces h+ ions in aqueous solution.

12. Acid is a species (a compound or ion) which donates or tends to donate a proton (h+).

13. An acid is a species (molecule or ion) which can accept a pair of electron. an acid is also called an electrophile (electron loving).

9. Methyle orange turns yellow in bases.

10. Those compounds, which provides hydroxyl (oh) ion in aqueous solution, are called bases.

11. A base is a substance, which gives (oh) in aqueous solution.

12. A base is a species, which accepts or tends to accept a proton.

13. A base is a species (molecule or ion) which can donate a pair of electron. an acid is also called a nucleophile (nucleus loving).

 

 

Question 3: Give some examples of acids and bases?

Answer: Examples of acids: HF, HCl, HBr, HI, H2S, HNO3, HNO2, H2SO4, H2 SO3, H3PO4, H3PO3, H2 CO3

Examples of Bases: LiOH, KOH, NaOH, CsOH, RbOH and H2O.

Mg(OH)2, Ca(OH)2, Ba(OH)2, Sr(OH)2

Al(OH)3, Sn(OH)2, Pb(OH)2, Fe(OH)2, Fe(OH)3

 

Question 4: Write down a detailed note on Arrhenius concepts of acids and bases?

 

Answer: Arrhenius Concept of Acids and Bases:

According to Arrhenius concept (1787):

Acid is a substance which dissociates in aqueous solution to give hydrogen ions.

 

For example, substances such as HCl, HNO3 , CH3 COOH, HCN, etc., are acids because they ionize in aqueous solutions to provide H+ ions.

10th Class Chemistry Chapter 10  Acids bases and salts

  H2SO4 + H2O H3O+ + HSO4

 

On the other hand, base is a substance which dissociates in aqueous solution to give hydroxide ions.

 

The substances such as NaOH, KOH, NH4 OH, Ca(OH)2 etc. are bases because these compounds ionize in aqueous solutions to provide OH ions.

NaOH > Na+ + OH‾

Ca(OH)2 ==> CaO + H2O

Thus, according to Arrhenius Concept:

Acids give H+ ions in water, bases give OH ions in water.

 

Examples of some important acids and bases are given in Table.

Table : Acids and Bases :

Acids Bases
Hydrochioric acid, HCI

Nitric acid, HNO3

Sulphuric acid, H2SO4

Phosphoric acid, H3PO4

Sodium hydroxide, NaOH

Potassium hydroxide, KOH

Calcium hydroxide, Ca(OH)2

Aluminium hydroxide, Al(OH)3

 

 

Limitation of Arrhenius concept:

  1. This concept is applicable only in aqueous medium and does not explain nature of acids and bases in non-aqueous medium.
  2. According to this concept, acids and bases are only those compounds which contain hydrogen (H+) and hydroxyl or hydroxide (OH) ions, respectively. It can’t explain the nature of compounds like CO2, NH3, etc. which are acid and base, respectively.

Although this concept has limited scope yet, it led to the development of more general theories of acid-base behaviour.

 

 

 

Question 5: Define an acid and a base according to Bronsted-Lowry concept and justify with examples that water is an amphoteric compound.

Answer: Bronsted-Lowry Concept : In 1923, the Danish chemist Bronsted and the English chemist Lowry independently presented their theories of acids and bases on the basis of proton-transfer.

According to this concept:  An acid is a substance (molecule or ion) that can donate a proton (H+) to another substance.

A base is a substance that can accept a proton (H+)from another substance.

 

For example, HCl acts as an acid while NH3 acts as a base:

 

It is a reversible reaction. In the forward reaction, HCl is an acid as it donates a proton, whereas H2O is a base as it accepts a proton. In the reverse reaction, Cl ion is a base as it accepts a proton from acid H3O+ ion. CI  ion is called a conjugate base of acid HCl and H3O+ ion is called a conjugate acid of base H2O. It means every acid produces a conjugate base and every base produces a conjugate acid such that there is conjugate acid-base pair. Conjugate means joined together as a pair.

A conjugate acid is a specie formed by accepting a proton by a base.

A conjugate base is a specie formed by donating a proton by an acid.

Thus, conjugate acid-base pair differs from one another only by a single proton.

Similarly,

 

 

 

Explanation: According to Bronsted-Lowry concept, an acid and a base always work together to transfer a proton. That means, a substance can act as an acid (proton donor) only when another substance simultaneously behaves as a base (proton acceptor). Hence, a substance can act as an acid as well as a base, depending upon the nature of the other substance. For example, H2O acts as a base when it reacts with HCl as stated above and as an acid when it reacts with ammonia such as:

 

 

Such a substance that can behave as an acid, as well as, a base is called amphoteric.

 

Limitation of Bronsted Lowry Concept: It has been observed that there are certain substances which behave as acids though they do not have the ability to donate a proton, e.g.,SO3 . Similarly, CaO behaves as a base but it cannot accept a proton. These observations prove the limitations of Bronsted-Lowry concept of acids and bases.

 

 

Do you know: All Arrhenius acids are Bronsted-Lowry acids, but except OH other Bronsted-Lowry bases are not Arrhenius bases.

 

Table : Conjugate Acids and Bases of common species

 

 

Acid   Base   Conjugate acid   Conjugate base
HNO3(aq) + H2O(I) <> H3O+(aq) + NO3 (aq)
H2SO4(aq) + H2O(I) <> H3O+(aq) + HSO4 (aq)
HCN(aq) + H2O(I) <> H3O+(aq) + CN (aq)
CH3COOH (aq) + H2O(I) <> H3O+(aq) + CH3COO (aq)
H2O(I) + NH3(aq) <> NH4+(aq) + OH (aq)
H2O(I) + CO32-(aq) <> HCO3 (aq) + OH (aq)
HCI(I) + HCO3 (aq) <> H2CO3(aq) + CI(aq)

 

 

 

Do You Know? All Arrhenius acids are Bronsted-Lowry acids, but except OH other Bronsted-Lowry bases are not Arrhenius bases

 

 

(c) Bronsted acids, as well as, bases are: H2O, HCO3, HS

 

 

Question 6: Explain the Lewis concept of acids and bases?

Lewis Concept of Acids and Bases:

The Arrhenius and Bronsted-Lowry concepts of acids and bases are limited to substances which contain protons. G.N. Lewis (1923) proposed a more general and broader concept of acids and bases. According to this concept:

An Acid is a substance (molecule or ion) which can accept a pair of electrons, while a base is a substance (molecule or ion) which can donate a pair of electrons.

For example, a reaction between ammonia and boron trifluoride takes place by forming a coordinate covalent bond between ammonia and boron trifluoride by donating an electron pair of ammonia and accepting that electron pair by boron trifluoride.

 

 

some other examples of lewis acids: FeCl3, FeBr3, AlCl3 etc. (Lewis acid)

 

 

The cations (proton itself or metal ions) act as Lewis acids. For example, a reaction between H+ and NH3 , where H+ acts as an acid and ammonia as a base.

NH3 + H+ > NH4+

 

The product of any Lewis acid-base reaction is a single species, called an adduct. So, a neutralization reaction according to Lewis concept is donation and acceptance of an electron pair to form a coordinate covalent bond in an adduct.

Acids are electron pair acceptors while bases are electron pair donors. Thus, it is evident that any substance which has an unshared pair of electrons can act as a Lewis base while a substance which has an empty orbital that can accommodate a pair of electrons acts as Lewis acid.

 

Examples of Lewis acids:  According to Lewis concept, the following species can act as Lewis acids:

 

Molecules in which the central atom has incomplete octet. For example, in BF3, AICI3, FeCl3, the central atoms have only six electrons around them, therefore, these can accept an electron pair.

(ii) Simple cations can act as Lewis acids. All cations act as Lewis acids since they are deficient in electrons. However, cations such as Na+, K+, Ca2+ ions, etc., have a very little tendency to accept electrons. While the cations like H+, Ag+ ions, etc., have a greater electron accepting tendency therefore, act as Lewis acids.

 

Lewis bases: According to Lewis concept, the following species can act as Lewis bases:

 

(i) Neutral species having at least one lone pair of electrons. For example, ammonia, amines, alcohols etc. act as Lewis bases because they contain a lone pair of electrons:

 

(ii) Negatively charged species or anions. For example, chloride, cyanide, hydroxide ions, etc., act as Lewis bases:

 

Question 7: Make a summary of different concepts of acids and bases?

Answer:

Summary of the Concepts.

Summary of the Concepts.

 

Concept

Acid Base Product
Arrhenius

Bronsted-Lowry

Lewis

give H+

donate H+

electron pair acceptor

give OH

accept H+

electron pair donor

salt + H2O

conjugate acid base pair

adduct

 

 

  Do you know:

It may be noted that all Bronsted bases are also Lewis bases but all Bronsted acids are not Lewis acids. According to Bronsted concept, a base is a substance which can accept a proton, while according to Lewis concept, a base is a substance which can donate a pair of electrons. Lewis bases generally contain one or more lone pair of electrons and therefore, they can also accept a proton (Bronsted base). Thus, all Lewis bases are also Bronsted bases. On the other hand, Bronsted acids are those which can give a proton. For example, HCI, H2SO4 are not capable of accepting a pair of electrons. Hence, all Bronsted are not lewis acids.

 

 

Question 8: Write a note on chemical properties of acids?

Answer: Chemical Properties of Acids:

(i) Reaction with Metals

Acids react explosively with metals like sodium, potassium and calcium. However, dilute acids (HCl, H2SO4) react moderately with reactive metals like: Mg, Zn, Fe and Al to form their respective salts with the evolution of hydrogen gas.

 

 

(ii) Reaction with Carbonates and Bicarbonates: Acids react with carbonates and bicarbonates to form corresponding salts with the evolution of carbon dioxide gas.

 

 

 

(iii) Reaction with Bases

Acids react with bases (oxides and hydroxides of metal and ammonium hydroxide) to form salts and water. This process is called neutralization.

 

(iv) Reaction with Sulphites and Bisulphites

Acids react with sulphites and bisulphites to form salts with the liberation of sulphur dioxide gas.

 

(v) Reaction with Sulphides

Acids react with metal sulphides to liberate hydrogen sulphide gas.

 

Do you know: Following acids are called mineral acids.

Hydrochloric acid (HCI)

Sulphuric acid (H2SO4 )

Nitric acid (HNO3)

 

 

 

 Question 9: Write a short note on naturally occurring acids?

Answser:

 

 

 

 

Naturally Occuring Acids
  Acid Source
I Citric acid Citrus fruits i.e., lemon, oranges
Ii Lactic acid sour milk
Iii Formic acid Stings of bees and ants
Iv Butyric acid Rancid butter
V Tartaric acid Tamarind, grapes, apples
Vi Malic acid Apples
Vii    Uric acid Urine
Viii   Stearic acid Fats

 

Question 10: Give an account of uses of acids?

Answer:  Uses of Acids

  1. Sulphuric acid is used to manufacture fertilizers, ammonium sulphate, calcium superphosphate, explosives, paints, dyes, drugs. It is also used as an electrolyte in lead storage batteries.
  2. Nitric acid is used in manufacturing of fertilizer (ammonium nitrate), explosives, paints, drugs and etching designs on copper plates.
  3. Hydrochloric acid is used for cleaning metals, tanning and in printing industries.

4 Benzoic acid is used for food preservation.

5 Acetic acid is used for flavouring food and food preservation. It is also used to cure the sting of wasps.

 

Question 11: What are the different chemical properties of bases?

Answer: Chemical Properties of bases:

 

(i) Reaction with Acids

Bases react with acid to form salt and water. It is a neutralization reaction.

(ii) Reaction with Ammonium Salts

Alkalies react with ammonium salts to liberate ammonia gas:

 

(iii) Precipitation of Hydroxides

Alkalis precipitate insoluble hydroxides when added to solutions of salts of heavy metals such as copper, iron, zinc, lead and calcium.

 

Question 11: Give uses of bases?

 

Answer: Uses of Bases:

  1. Sodium hydroxide is used for manufacturing of soap.
  2. Calcium hydroxide is used for manufacturing of bleaching powder, softening of hard water and neutralizing acidic soil and lakes due to acid rain.
  3. Potassium hydroxide is used in alkaline batteries.
  4. Magnesium hydroxide is used as a base to neutralize acidity in the stomach. It is also used for the treatment of bee’s stings.
  5. Aluminium hydroxide is used as foaming agent in fire extinguishers.
  6. Ammonium hydroxide is used to remove grease stains from clothes.

 

Science, Society and Technology:

Stomach acidity

Stomach secretes chemicals in a regular way to digest food. These chemicals mainly consist of hydrochloric acid along with other salts. Although, hydrochloric acid is highly corrosive, but stomach is protected from its effects because it is lined with cells that produce a base. The base neutralizes stomach acid. The important function of this acid is to break down chemical bonds of foods in the digestion process. Thus, big molecules of food are converted into small ones. It also kills the harmful bacteria of certain foods and drinks.

However, sometimes stomach produces too much acid. It causes stomach acidity also called hyperacidity. Symptoms of this disease are feeling burning sensation throughout the gastro intestinal track. These feelings sometimes extend towards the chest, that is called heart burning.

The best prevention from hyperacidity is:

i) Avoiding over-eating and staying away from fatty acids and spicy foods.

ii) Simple and regular eating, remaining in an upright position for about 45 minutes after taking a meal.

iii) Keeping the head elevated while sleeping.

 

Science , Society and Technology:

Process of Etching in Art and Industry:

The process of etching on glass is carried out by using a wax stencil. Stencil is placed on areas of glass or mirror that are to be saved from acid. The glass or mirror is dipped into hydrofluoric acid. The acid dissolves the exposed part of the glass thus etching it. This process has been very dangerous because the acid would damage the skin and tissue of artist’s body. Although, it is dangerous to deal with acid, yet etching done with acid is very attractive as compared to using other chemicals.

 

Question 12: What is auto-ionization of water? How is it used to establish the pH of water? What are the different uses of PH scale?

Answer: The self-ionization of water (also autoionization of water, and autodissociation of water) is an ionization reaction in pure water or an aqueous solution, in which a water molecule, H2O, deprotonates(loses the nucleus of one of its hydrogen atoms) to become a hydroxide ion, OH. The hydrogen nucleus, H+, immediately protonates ( protonation is the addition of a proton (H+) to an atom, molecule, or ion, forming the conjugate acid)  another water molecule to form hydronium, H3O+. It is an example of autoprotolysis, and exemplifies the amphoteric nature of water.

 

 

PH

Definition: PH SCALE: pH is the negative logarithm of molar concentration of the hydrogen ions.  OR   PH is the logrithmatic measure of hydrogen ion concentration in aquesous solution.

Explanation: Concentration of hydrogen ion [H+] in pure water is the basis for the pH scale. Water is a weak electrolyte because it ionizes very slightly into ions in a process called auto-ionization or self-ionization;

 

 

The equilibrium expression of this reaction may be written as
 Kc = [H+] [OH]/ H2O
As concentration of water (H2O) is almost constant. The above equation may be written as
A new equilibrium constant known as ionic product constant of water ‘Kw’ is used instead of product of equilibrium constant and [H2O]. Therefore,
As we know, one molecule of water produces one H+ ion and one OH ion on dissociation so

 

 

As it is difficult to deal with such small figures having negative exponents, so it is convenient to convert these figures into a positive figure using a numerical system. It is taking the common (base-10) logarithm of the figure and multiplying it with -1. ‘p’ before a symbol means’ negative logarithm of the symbol. So ‘p’ before H means negative logarithm of [H+]. Therefore, pH is the negative logarithm of molar concentration of the hydrogen ions. That is,

With reference to this equation, a scale develops according to the molar concentration of H+ ions that is called pH scale. It ranges from 0 to 14. According to this scale, pH of water is calculated as:

Similarly

pH value normally varies from 0 to 14. Therefore:

So, the sum of the pH and pOH of the solution is always 14 at 25 °C. Such as;

 

A solution of a compound of pH 7 or pOH 7 is considered a neutral solution. Solutions of pH less than 7 are acidic and more than 7 are basic.

 

 

Since the pH scale is logarithmic, a solution of pH 1 has 10 times higher concentration of [H+] than that of a solution of pH 2; 100 times than that of a solution of pH 3 and so on. Hence, low pH value means strong acid while high pH value means a strong base and vice versa.

Conclusion

(i) pH of a neutral solution is always 7.

(ii) Acidic solutions have pH less than 7.

(iii) Basic solutions have pH value greater than 7.

(iv) pH and pOH values range from 0 to 14.

 Uses of pH

(i) It is used to determine acidic or basic nature of a solution.

(ii) It is used to produce medicines, culture at a microbiological particular concentration of H+ ion.

(iii) It is used to prepare solutions of required concentrations necessary for certain biological reactions.

Question 13: Define autoprotolysis?

Answer: In autoprotolysis a proton is transferred between two identical molecules, one of which acts as a Brønsted acid, releasing a proton which is accepted by the other molecule acting as a Brønsted base. For example, water undergoes autoprotolysis in the self-ionization of water reaction.

H2O + H2O >  OH + H3O+

Any solvent that contains both acidic hydrogen and lone pairs of electrons to accept H+ can undergo autoprotolysis.

For example, ammonia in its purest form may undergo autoprotolysis:

 

2NH3 >  NH2 + NH4+

 

Question 14: What is an indicator? What are the different types of indicators used in the labortary? How PH of a solution is measured?

Answer: Indicators: Indicators are the organic compounds that give different colours in acidic and alkaline solutions and are used for the identification of acids and bases.

 

Explanation: Litmus is a common indicator. It is red in acidic solutions and blue in alkaline solutions.

Each indicator has a specific color in acidic medium which changes at a specific pH to another color in basic medium. For example, phenolphthalein is colorless in strongly acidic solution and red in strongly alkaline solution. It changes color at a pH of about 9. This means phenolphthalein is colorless in a solution with pH less than 9. If the pH is above 9, phenolphthalein is red as is shown in figure.

Figure:. . Colors of indicators at different pH solutions.

 

A few commonly used indicators in titrations are given in Table

 

Table: Few important indicators
Indicator Color in strongly acidic solution pH a which color changes Color in strongly alkaline solution
Methyl orange

 

Litmus

 

Phenolphthalein

 

red

 

red

 

colourless

4

 

7

 

9

Yellow

 

blue

 

red

 

Measuring pH of a Solution

(i) Universal Indicator OR PH indicator:

Some indicators are used as mixtures. The mixture indicator give different colors at different pH values. Hence, it is used to measure the pH of a solution. Such a mixed indicator is called Universal Indicator or simply pH indicator. The pH of solution can be measured by dipping a piece of Universal Indicator paper in the solution. The pH is then found by comparing the color obtained with a color chart as shown in figure.

Figure:. Colours of universal indicator

 

 

(ii) The pH Meter: The pH of a solution can be measured with a pH meter. It consists of a pH electrode connected to a meter. The electrode is dipped into the solution and the meter shows the pH either on a scale or digitally. It is much more reliable and accurate method of measuring pH than Universal Indicator paper, though the latter is often more convenient.

 

Question 15: Why the p in pH is lower case or small?

Answer: pH is an old abbreviation for a french description of the acidity of water.The French term is “puissance d’hydrogen”, which means “power or strength of Hydrogen”. The p is small because it refers to a word. The H must be capitalized because the first letter of abbreviations for chemical elements (in this case Hydrogen) are always capitalized.

  Areas of work for analytical chemists.

Analytical chemist examine substances qualitatively and quantitatively. They identify substances and evaluate their properties.

 

They have a wide area for working ranging from basic research in laboratories to analytical research in industries. They work in almost all industries including manufacturing, pharmaceuticals, healthcare, forensics and public protection – where they test air, water, industrial waste, drugs and food to make sure they are safe. They ensure the quality of the products in industry.

 

Question 16: Define a salt and give the characteristic properties of salts.

 

SALTS: Salts are ionic compounds generally formed by the neutralization of an acid with a base.

Salts are made up of positive ions (cations) and negative ions (anions). A cation is metallic ion derived from a base, therefore, it is called basic radical. While anion is derived from an acid, therefore, it is called acid radical.

A salt gets its name from the names of the metal and the acid as shown in Table:

 

Table: Acids and their Salts

Metal Acid Salt name
Sodium (Na)
Potassium (K)Zinc (Zn)Calcium (Ca)

 

Silver (Ag)

Hydrochloric acid (HCl)
Nitric acid (HNO3)Sulphuric acid (H2SO4)Phosphoric acid (H3PO4)

 

Acetic acid (CH3COOH)

Sodium chloride (NaCl)
Potassium nitrate (KNO3)Zinc sulphate (ZnSO4)Calcium phosphate Ca3 (PO4)2

 

Silver acetate (CH3COOAg)

 

 

Characteristic properties of salts

(i) Salts are ionic compounds found in crystalline form.

(ii) They have high melting and boiling points.

(iii) Most of the salts contain water of crystallization which is responsible for the shape of the crystals. Number of molecules of water
are specific for each salt and they are written with the chemical formula of a salt. For example, Copper sulphate CuSO4 .5H2O; Calcium sulphate CaSO4 2H2O

(iv) Salts are neutral compounds. Although, they do not have equal number of positive and negative ions, but have equal number of positive and negative charges.

 

Question 17: Explain with examples that how are soluble and insoluble salts prepared?

 

Answer: Preparation of salts: Salts may be water soluble or insoluble. The methods used for the preparation of salts are based on their solubility in water.

General Methods for the Preparation of Salts:

There are five general methods for the preparation of salts. Four methods make soluble salts but one prepares insoluble salts.

 

 (i) Preparation of soluble salts:

Soluble salts are often prepared in water. Therefore, they are recovered by evaporation or crystallization.

 

(a) By the reaction of an acid and a metal: (Direct Displacement method)

This is direct displacement method in which hydrogen ion of acid is replaced by a reactive metal. Such as calcium, magnesium, zinc and iron, e.g.

(b) By the reaction of an acid and a base: (Neutralization method)

It is a neutralization reaction in which acid and base react to produce a salt and water.

 

 

(c) By the reaction of an acid and metallic oxide:

Mostly the insoluble metallic oxides react with dilute acids to form salt and water

 

 

(d) By the reaction of an acid and a carbonate:

Dilute acids react with metallic carbonates to produce salts, water and carbon dioxide gas.

 

(ii) Preparation of insoluble salts:

In this method, usually solutions of soluble salts are mixed. During the reaction exchange of ionic radicals (i.e., metallic radicals exchange with acidic radicals) takes place to produce two new salts. One of the salts is insoluble and the other is soluble. The insoluble salt precipitates (solidify in solution).

 

 

Question 18:  What are the different types of salts?  Give the characteristics of an acidic salt?

Answer: Types of Salts:

Following are the main classes of salts.

(i) Normal salts (ii) Acidic salts

(iii) Basic salt (iv) Double salts

(v) Mixed salts (vi) Complex salts

 

(i) Normal or Neutral Salts: A salt formed by the total replacement of ionizable H+ ions of an acid by a positive metal ion or NH4+ ions is called normal or neutral salt. These salts are neutral to litmus, that is,

 

HCl + KOH > KCl + H2O

 

(ii) Acidic Salts: These salts are formed by partial replacement of a replaceable H+ ions of an acid by a positive metal ion. A salt formed between a strong acid and a weak base is an acid salt.

 

 

Properties of Acidic salts:

*Acidic salts react with bases to form normal salts.

*These salts turn blue litmus red.

 

(iii) Basic Salts

Basic salts are formed by the incomplete neutralization of a polyhydroxy base by an acid.

(iv) Double Salts

Double salts are formed by two normal salts when they are crystallized from a mixture of equimolar saturated solutions. The individual salt components retain their properties. The anions and cations give their respective tests. Mohr’s salt FeSO4 (NH4 )2 SO4 6H2 O; Potash alum K2SO4 . Al2(SO4)3 . 24H2O; Ferric alum K2SO4 . Fe2(SO4)3 . 24H2O, are examples of double salts.

 

 

(v) Mixed Salts

Mixed salts contain more than one basic or acid radicals. Bleaching powder Ca(OCl) CI, is an example of mixed salts.

 

(vi) Complex Salts

Complex salts on dissociation provides a simple cation and a complex anion or vice versa. Only the simple ions yields the characteristics test for cation or anion. For example:

 

Potassium ferrocyanide K4 [Fe(CN)6) gives on ionization, a simple cation K+and complex anion [Fe (CN)6]– 4.

 

Question 19: Give uses of Salts?

Answer: Uses of Salts:

Salts have vast applications in industries and in our daily life. Some common salts and their uses are given in Table.

Table : Uses of Salts

Name of salts Common and Industrial Uses
Sodium chloride

(NaCI)

It is commonly used as a table salt and for coocking purposes, it is also used for de-icing roads in winter and for the manufacture of sodium metal, caustic soda, washing soda.
Sodium carbonate

Na2CO2) Soda

ash

It is used for the manufacture of glass, detergents, pulp and paper and other chemicals.
Sodium

carbonate

Na2CO3, 10H2O)

Washing soda

It is used as cleaning agent for domestic and commercial purposes, for softening of water, in manufacture of chemicals like caustic soda (NaOH), borax, glass, soap and paper.
Sodium sulphate (Na2SO4) It is used for the manufacture of glass, paper and detergents.
Sodium silicate

(Na2SiO3)

It is used for the manufacture of detergents, cleaning agents and adhesives.
sodium chlorate

(NaCIO3)

It is used for manufacture of explosives, plastics and other chemicals.
Sodium tetraborate

(Na2B4O7.10H2O)

It is used for manufacture of heat resistance glass (pyrex), glazes and enamels, in leather industry for soaking and cleaning hides.

 

Calcium chloride

(CaCI2)

It is used for de-icing roads in winter, as a drying agent of chemical reagents and as freezing agent.
Calcium oxide (CaO) Quick lime It is used as drying agent for gases and alcohol and in steel making, water treatment and other chemicals like slaked lime, bleaching powder, calcium carbide. For purification of sugar, a mixture of CaO and NaOH called soda lime is used to remove carbon dixide and water vapours from air.
Calcium sulphate

(CaSO4. 2H2O)

Gypsum is used as fertilizer, to prepare plaster of Paris which is use for making statues, casts, etc.
Potassium

Nitrate (KNO3)

It is used as fertilizer and for the manufacture of flint glass.

 

 

 

 

Question 20: What is meant by neutralization reaction?

 

Answer: Neutralization Reaction;

A reaction between an acid and a base is called a neutralization reaction. It produces a salt and water. A balanced chemical reaction is given here:

NaOH + HCl > NaCl + H2O

 

  Preservatives in food

Chemicals used to prevent food spoilage are called preservatives. Food spoiling may be due to microbial actions or chemical reactions. So preservatives serve as either anti-microbial or antioxidants or both.

Manufacturers add preservatives mostly to prevent spoiling during transportation and storage of foods for a period of time.

Natural food preservatives are salts, sugar, alcohol, vinegar, etc. They efficiently control the growth of bacteria in food. They are used to preserve meat, fish, etc.

 

 

Science , Society and Technology:

Acid Rain

Acid rain is formed by dissolving acidic air pollutants like oxides of sulphur and nitrogen by rain water. As a result pH of the rain water decreases, i.e., it becomes acidic. When this acid rain falls down, it damages animals, plants, buildings, water bodies and even soil.

 

Short Questions

  1. Name three common household substances having
  2. pH value greater than 7
  3. pH value less than 7
  4. pH value equal to 7

 

 

Answer:

 

  1. a) common household substances having PH value greater than 7.

J Sodium bicarbonate OR Baking soda (NaHCO3).

J  Ammonia (NH3).

J  Washing soda (Na2CO3).

J Lime water  or Ca(OH)2

 

  1. b) Common household substances having pH value less than 7.

J  Vinegar or acetic acid (CH3COOH).

J Lemon, orange, guava, etc. contain citric acid (C6H8O7).

J Apple contain malic acid (C4H6O5).

J Sour milk or yogurt contain lactic acid (C3H6O3).

 

  1. c) common household substances having pH value equal to 7.

J Sodium chloride (NaCl).

J Water (H2O)

J Cooking oil.

J Sucrose (C12H22O11).

  1. Define a base and explain all alkalies are bases, but all bases are not alkalies.

Answer: Base is a substance which release OH- ions in water. Or Base is a substance which can accept a proton Or base is a substance which donate a pair of electron to another substance. alkalies are a group of water soluble bases. All bases are not soluble in water. So all bases are not alkalies but all bases are alkalies.

 

  1. Define Bronsted-Lowry base and explain with an example that water is a Bronsted-Lowry base.

Answer: According to Bronsted-Lowry “ Base is a substances that can accept a pair of electrons from another substance. Water is Bronsted-Lowry base, because it has the ability to accept a proton.

e.g.

 

  1. How can you justify that Bronsted-Lowry concept of acid and base is applicable to non-aqueous solutions?

Answer: According to Bronsted-Lowry concept:

“An acid is a substance which donate a proton”.

“A base is a substance which can accept a proton”.

So according to this concept there is no need of water or no need of H+ or OH ions. So it is applicable to non-aqueous substances.

 

  1. Which kind of bond forms between Lewis acid and a base?

Answer: Coordinate covalent bond (Dative bond) is formed between lewis acid and a lewis base.

  1. Why H+ion acts as a Lewis acid?

Answer: According to Lewis concept “ An acid is a substance which accept a pair of electrons from another substance. As H+ ion has the ability to accept a pair of electrons. So it act as a Lewis acid.

 

  1. Name two acids used in the manufacture of fertilizers.

Answer: HNO3 and H2SO4 are used in the manufacture of fertilizers.

 

  1. Define pH. What is the pH of pure water?

Answer: PH is the negative logarithm of molar concentration of the hydrogen ion.

The PH of pure water is 7.

 

 

  1. How many times a solution of pH 1 will be stronger than that of a solution having pH 2?

Answer: A solution of PH 1 will be 10 times stronger than that of a solution having PH 2.

 

 

 

  1. Define the followings:

 

  1. Normal salt ii. Basic salt

Answer:

Normal or Neutral Salts: A salt formed by the total replacement of ionizable H+ ions of an acid by a positive metal ion or NH+4 ions is called normal or neutral salt. These salts are neutral to litmus.

Basic Salts:

Basic salts are formed by the incomplete neutralization of a polyhydroxy base by an acid.

 

 

  1. Na2SO4 is a neutral salt while NaHSO4 an acid salt. Justify.

Answer: Na2SO4 is a neutral salt because it is formed by complete replacement of H+ ions of acid by a base (metal), while NaHSO4 is an acidic salt because it is formed by incomplete or partial replacement of H+ ions of an acid by a base.

 

  1. Give a few characteristic properties of salts.

Answer: Characteristic properties of salts:

(i) Salts are ionic compounds found in crystalline form.

(ii) They have high melting and boiling points.

(iii) Most of the salts contain water of crystallization which is responsible for the shape of the crystals. Number of molecules of water
are specific for each salt and they are written with the chemical formula of a salt. For example, Copper sulphate CuSO4 .5H2O; Calcium sulphate CaSO4 2H2O

(iv) Salts are neutral compounds. Although, they do not have equal number of positive and negative ions, but have equal number of positive and negative charges.

 

  1. How are the soluble salts recovered from water?

Answer: The soluble salts are recovered from water by crystallization or evaporation.

 

  1. How are the insoluble salts prepared?

Answer: Preparation of insoluble salts:

In this method, usually solutions of soluble salts are mixed. During the reaction exchange of ionic radicals (i.e., metallic radicals exchange with acidic radicals) takes place to produce two new salts. One of the salts is insoluble and the other is soluble. The insoluble salt precipitates (solidify in solution).

 

  1. Why a salt is neutral, explain with an example?

Answer: Salts are neutral compounds. Although, they do not have equal number of positive and negative ions, but have equal number of positive and negative charges.

Example: Mg+2Cl2-2 .

In magnesium chloride magnesium has one ion while ions of chlorine are 2. The ions of magnesium are less in amount than chloride ions. But still it is a neutral compound because the charges on both magnesium and chlorine are same and so they cancel each other.

 

  1. Name an acid used in the preservation of food.

Answer: Acetic acid is used in the preservation of food.

 

  1. Name the acids present in:
  2. Vinegar ii. Ant sting iii. Citrus fruit iv. Sour milk

 

Answer: i) Vinegar à Acetic acid (CH3COOH).

  1. ii) Ant sting àFormic acid (HCOOH).

iii. Citrus fruit à Citric acid (C6H8O7).

  1. Sour milk àLactic acid (C3H6O3).

 

  1. How can you justify that Pb(OH)NO3 is a basic salt?

Answer: Basic salts are formed by incomplete or partial replacement of OH- ion of a base by an acid. As Pb(OH)NO3 is formed by partial replacement of OH- ion by an acid or it contain an OH- group, so it is a basic salt.

 

  1. You are in a need of an acidic salt. How can you prepare it?

Answer: Acidic Salts: These salts are formed by partial replacement of a replaceable H+ ions of an acid by a positive metal ion. It is formed by the reaction between a strong acid and a weak base.

 

  1. Which salt is used to prepare plaster of Paris?

Answer: Calcium sulphate (CaSO4. 2H2O) or gypsum is used to prepare plaster of Paris.

 

 

Extensive Questions:

 

  1. Define an acid and a base according to Bronsted-Lowry concept and justify with examples that water is an amphoteric 
    compound.

Answer: Please see answer of question no.5.

 

  1. Explain the Lewis concept of acids and bases.

Answer: Please see answer of question no. 6.

 

  1. What is auto-ionization of water? How is it used to establish the pH of water?

Answer: Please see answer of question no. 12.

 

  1. Define a salt and give the characteristic properties of salts.

Answer: Please see answer of question no. 16.

 

  1. Explain with examples that how are soluble salts prepared?

Answer:  Related to question no. 17.

 

 

  1. Give the characteristics of an acidic salt.

Answer: Please see answer of question no. 18.

 

 

  1. Give four uses of calcium oxide.

Answer: Please see answer of question no. 19

 

 

  1. You are having a strong acid (HNO3) and strong base (NaOH) on mixing 
    i. What type of salt you will have?
  2. What type of this reaction will be?

iii. Will it be soluble or insoluble salt?

  1. If it is soluble, how it will be recovered?

 

Answer: i) We obtain a neutral salt or normal salt on mixing a strong acid and a strong base.

e.g. HCl + NaOH à NaCl + H2O.

  1. ii) This type of reaction is called neutralization reaction.

iii) The salt obtained will be soluble.

  1. iv) It can  be recovered by crystallization or evaporation techniques.

 

 

  1. Explain why:
  2. HCl forms only one series of salts.
  3. H2SO4 forms two series of salts.

 iii. H3PO4 form three series of salts.

Give necessary equations.

Answer:

  1. i) HCl forms only one series of salt because it has only one ionizeable proton as H+ ion.

HCl à H+ + Cl

Example: HCl + NaOH à NaCl + H2O.

  1. ii)  H2SO4 forms two series of salts because it has two ionizeable proton as H+ ions.

H2SO4 à H+ + HSO4

HSO4  à H+ + SO4

Example: NaOH + H2SO4 à NaHSO4 + H2O

NaHSO4 + NaOH à Na2SO4 + H2O.

iii) H3PO4 forms three series of salts because it has three ionizeable protons as H+ ions.

H3PO4 à H++ H2PO4

H2PO4à H+ + HPO4-2

HPO4-2 à H+ + PO4-3

 

Example: H3PO4 + NaOH à NaH2PO4 (Monosodium phosphate)  + H2O.

NaH2PO4 + NaOH à Na2HPO4 (Disodium phosphate) + H2O.

Na2HPO4 + NaOH à Na3PO4 (Trisodium phosphate) + H2O.

 

 

  1. Classify the following salts as soluble or insoluble salts:
  2. Sodium chloride ii. Silver nitrate

iii. Lead chloride iv. Copper sulphate

  1. Barium sulphate vi. Ammonium chloride

vii. Sodium carbonate viii. Calcium carbonate

  1. Ferric chloride x. Magnesium sulphate

 

Answer:

  1. i) Sodium chloride (NaCl) àSoluble salt.
  2. ii) Silver nitrate (AgNO3) àSoluble salt.

iii)  Lead chloride ( PbCl2) à Insoluble.

  1. iv) Copper sulphate (CuSO4) à
  2. v)  Barium sulphate ( BaSO4) à
  3. vi) Ammonium chloride ( NH4Cl) à

vii) Sodium carbonate (Na2CO3) à Soluble.

viii) Calcium carbonate ( CaCO3) à Insoluble.

  1. Ferric chloride ( FeCl3) àSoluble.
  2. Magnesium sulphate ( MgSO4) àSoluble.

 

 

Keep some base rules in mind.

 

1/ All (or almost all) alkali metal salts and ammonium salts are soluble.

2/ All nitrates and acetates (except silver acetates) are soluble.

3/ All chlorides, bromides and iodides, except silver, mercury(I), copper(I) and lead(II), are soluble.

4/ All sulfates, except barium, strontium, calcium, silver and lead(II), are soluble or slightly soluble.

5/ All carbonates, except the group 1 and ammonium carbonates, are insoluble.

6/ All hydroxides, except the group 1 and ammonium, barium, strontium and calcium hydroxides, are insoluble.

NaCl – is a group 1 salt, so is soluble.

PbSO4 – is an insoluble sulfate.

Zn(NO3)2 – all nitrates are soluble.

CaCO3 – is not a group 1 carbonate, so it is insoluble.

Fe2(SO4)3 – is a slightly soluble sulfate.

PbCl2 – is an insoluble chloride.

K2SO4 – is a group 1 salt, so is soluble.

CuCO3 – is not a group 1 carbonate, so it is insoluble.

AgCl – insoluble chloride

Al(NO3)3  all nitrates are soluble.

BaSO4  insoluble sulfate

NH4Cl – ammonium salts are soluble.

 

 

  1. Complete and balance the following equations:

 

Answer:

 

Aluminum chloride + Hydrogen

 

 

Copper sulphate + water

 

 

 

 

Ferric sulphate + Hydrogen sulphide

FeS + H2SO4 > FeSO4 + H2S

 

 

 

Sodium chloride + Ammonia + Water.

NH4Cl + NaOH > NaCl + NH3 + H2O

 

 

 

Ferric hydroxide + Sodium chloride

 

 

 

 

 

 

1. What is the difference between Arrhenius base and Bronsted-Lowry base?

Answer: Difference between Arrhenius base and Bronsted-Lowry base.

 

Arrhenius Base Bronsted-Lowry Base
1) Arrhenius base is a substance which can dissociates in aqueous solution to give hydroxide ions. Bronsted-Lowry Base is a substance that can accept a proton from other substance.
2) Arrhenius bases are only those compounds that contain a hydroxyde (OH) group. It is not necessary that each and every Bronsted base contain OH group.

 

 

2. What do you mean by neutralization reaction according to Arrhenius acid-base concept?

Answer: According to Arrhenius concept the OH- group of a base combined with the H+ group of an acid to form water while the metallic ion of the base react with the negative ion of the acid to form salt. It is neutralization reaction as it produces salt and water.

 

3. Prove that water is an amphoteric specie.

Answer: Substance that behave both as an acid and a base is called amphoteric substance. Water behave both as an acid and a base depending upon the condition. Water when react with acids accept a proton from acid and act as a base. E.g;

HCl + H2O  > H3O+ + Cl

Water when react with bases donate a proton to base and act as acids. Such as:

H2O + NH3 > NH4+ + OH

 

4. How can you justify that NH3 is Bronsted-Lowry base but not Arrhenius base?

Answer: According to Arrhenius base is a substance that gives hydrogen ion in water while according to Bronsted-lowry concept base is a substance that accept a proton. As NH3 has no hydroxide ion so it is not an Arrhenious base but it is a Bronsted-Lowry base because it has the ability to accept a proton.

 

5. State and explain the neutralization reaction according to Lewis concept?

Answer: A neutralization reaction according to Lewis concept is donation and acceptance of an electron pair to form a coordinate covalent bond in an adduct.

 

6. Define and give the characteristics of a Lewis acid.

Answer: A Lewis acid is a substance (molecule or ion) which can accept a pair of electrons.

Characteristics of Lewis acids: i) Molecules in which the central atom has incomplete octet. For example, in BF3 , AICI3 , FeCl3 , the central atoms have only six electrons around them, therefore, these can accept an electron pair.

(ii) Simple cations can act as Lewis acids. All cations act as Lewis acids since they are deficient in electrons. However, cations such as Na+, K+, Ca2+ ions, etc., have a very little tendency to accept electrons. While the cations like H+, Ag+ ions, etc., have a greater electron accepting tendency therefore, act as Lewis acids.

 

7. Why BF3 behaves as a Lewis acid?

Answer: Lewis acid is a substance that has the ability to accept a pair of electrons. BF3 has an empty orbital. It means that BF3 is an electron deficient compound. To complete its octet BF3 accept a pair of electron and so it act as a lewis acid.

 

 

8. Water is an amphoteric specie according to Bronsted- Lowry concept. What is its nature according to Lewis concept?

Answer: An amphoteric species is a substance that can behave both as an acid (donate a proton) and a base (accept a proton).

Example: Water.

H2O (acid) + H2O (Base) → H3O+ + OH

Nature of water according to Lewis concept: According to Lewis concept acid is a substance that can accept a pair of electrons while base is a substance which can donate a pair of electrons. So according to this concept water is a base as it has a free or lone pair of electrons and has the ability to donate it through a coordinate covalent bond to form an adduct.

 

H2O + H+ H3O+ (Hydronium ion)

 

 

 

 

 

 

 

 

Test Yourself 10.2

1. When acids react with carbonates and bicarbonates, which gas evolves out?

Answer: When acid react with carbonates and bicarbonates Carbon dioxide gas is evolved.

 

2. Which types of salts produce SO2 gas on reacting with acids?

Answer: Reaction with Sulphites and Bisulphites

Acids react with sulphites and bisulphites to form salts with the liberation of sulphur dioxide gas.

 

 

 

Reaction with Sulphides:

Acids react with metal sulphides to liberate hydrogen sulphide gas.

 

 

3. Give the uses of sulphuric acid.

Answer: Uses of Sulphuric acid: Sulphuric acid is used to manufacture fertilizers, ammonium sulphate, calcium superphosphate, explosives, paints, dyes, drugs. It is also used as an electrolyte in lead storage batteries.

 

4. Name the gas liberated when alkalies react with ammonium salts.

Answer: When alkalies react with ammonium salts it produces ammonia gas.

 

 

 

5. Write down the colors of the precipitates formed by reaction of aqueous caustic soda with solutions of: copper, zinc and ferric salts.

Answer: Reaction of caustic soda with copper salts produces blue precipitate.

Reaction of caustic soda with zinc salts produce white precipitate.

Reaction of caustic soda with ferric salts produces dirty green precipitate

 

6. Name an alkali used in alkaline batteries.

Answer: Potassium hydroxide is used in alkaline batteries.

 

 

Test yuourself 10.3

 

1. Why pure water is not a strong electrolyte?

Answer: Pure water very slightly or partially ionizes into its ions at room temperature, so it is not a strong electrolyte.

2. HCI and H2SO4 are strong acids. While their solutions are equimolar, they have different pH value as calculated in problem 10.2 and 10.4. Why they have different pH values?

Answer: HCl has only one ionizeable hydrogen ion. It is monobasic acid. It produces one hydrogen ion on decomposition.

 

 

 

PH of HCl = -log [1×H+]

 

H2SO4 has two ionizeable hydrogen ions. It is a dibasic acid. It produces two hydrogen ions on decomposition.

 

H2SO4  à  2H+ + SO4-2

 

PH of H2SO4 = -log [2×H+]

 

So that the equimolar values of HCl and H2SO4 have different PH values.

 

3. Why ionic-product constant of water is temperature dependent?

Answer: Kw is the ionic product constant. It is temperature dependent.

Because with the increase of temperature the decomposition of water molecules into ions increases.

 

4. Differentiate between ‘p’ and pH.

Answer: “p” before any symbol means negative logarithm of that symbol. So “p” before “H” means negative logarithm of molar concentration of the hydrogen ions.

PH = -log [H+]

 

Test yourself 10.4:

 

1. How are the salts named?

Answer: A salt gets its name from the   names of the metals (base) and the acid.

For example:

HCl + NaOH à NaCl + H2O

The salt NaCl (Sodium chloride) contains two types of ions. Na+ ion from the base and Clion from the acid.

 

2. Name the salts which are formed when Zn metal reacts wixth following acids.

a . nitric acid . phosphoric acid c. acetic acid.

Answer:

a) Zinc (Zn) + Nitric acid à Zn(NO3)2 or Zinc nitrate.

b) Zinc (Zn) + Phosphoric acid à Zn(PO4)2 OR Zinc phosphate.

c) Zinc (Zn) + Acetic acid à ZnC4H6O4 OR Zn(O2CCH3)2 or Zinc acetate.

 

 

3. How will you justify salts are neutral compounds?

Answer:  Although, Salts do not have equal number of positive and negative ions, but have equal number of positive and negative charges, so they are neutral compounds.

Example: Mg+2Cl2-2 .

In magnesium chloride magnesium has one ion while ions of chlorine are 2. The ions of magnesium are less in amount than chloride ions. But still it is a neutral compound because the charges on both magnesium and chlorine are same and so they cancel each other.

 

 

4. How many water of crystallizations are present in CuSO4-5H2 O and CaSO4– .2H2O?

Answer: There are 5 molecules of water of crystallization in CuSO4.5H2O, while in CaSO4.2H2O there are two water of crystallization.

 

 

5. Name the type of reaction that takes place between an acid and a metal. Which gas would evolve in the reaction? Explain with an example.

Answer: The reactions that takes place between an acid and a metal are called direct displacement reactions. In these reactions, the hydrogen ion of the acid is directly replaced by  a reactive metal. Such as calcium, magnesium, zinc and iron, e.g.

 

 

 

 

Read Also Chapter 9 of 10th Class Chemistry

 

Test yourself 10.5

1. Name the types of salts.

Answer:  Types of Salts

Following are the main classes of salts.

(i) Normal salts (ii) Acidic salts

(iii) Basic salt (iv) Double salts

(v) Mixed salts (vi) Complex salts.

 

2. H3PO4 is a weak acid but its salt (Na3PO4 ) with strong base NaOH is neutral. Explain it.

Answer: The strong base like NaOH has the ability to accept all hydrogen ions from the weak acid like H3PO4. And that is the reason the salt formed is a neutral salt.

H3PO4 + 3NaOH à Na3PO4 + 3H2O.

 

 

3. How the basic salts turns into normal salts? Explain with an example.

Answer: Basic salts turns into normal salts when they react with acids.

e.g. Basic salt Zn(OH)NO3 react with HNO3 (Nitric acid) to form Normal or neutral salt (ZnNO3).

 

 

 

 

4. What are complex salts.

Answer: (vi) Complex Salts

Complex salts on dissociation provides a simple cation and a complex anion or vice versa. Only the simple ions yields the characteristics test for cation or anion. For example: Potassium ferrocyanide K4 [Fe(CN)6) gives on ionization, a simple cation K+and complex anion [Fe(CN)6]– 4.

 

5. Na2SO4 is a neutral salt. What are its uses?

Answer:  It is used for the manufacture of glass, paper and detergents.

 

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