Samacheer Kalvi 9th Science Solutions Chapter 14 Pdf

Samacheer Kalvi 9th Science Solutions Chapter 14 Pdf

Tamilnadu Board Samacheer Kalvi 9th Science Solutions Chapter 14: Tamilnadu State Board Solution Class 9 Science Chapter 14 – ACIDS, BASES AND SALTS.

Samacheer Kalvi 9th Science Solutions Chapter 14: Overview   

Board	Samacheer Kalvi
Class	9
Subject	Science
Chapter	14
Chapter Name	ACIDS, BASES AND SALTS

Samacheer Kalvi 9th Science Solutions Chapter 14 Pdf

 

Chapter 14 

Acids, bases and salts

 

Choose the correct answer.

1) Zn + 2 HCl → ZnCl2 + …↑ (H2, O2, CO2)

Ans: H₂

Because, Zn + 2 HCl → ZnCl₂ + H₂

2) Apple contains malic acid. Orange contains (citric acid, ascorbic acid).

Ans: Citric acid

Because, in orange and lemon citric acid is present.

3) Acids in plants and animals are organic acids. Whereas Acids in rocks and minerals are (Inorganic acids, Weak acids).

Ans: Inorganic acids

Because, rocks and minerals are the inorganic compounds.

4) Acids turn blue litmus paper to (green, red, and orange).

Ans: Red

Because, acid turns blue litmus paper to red.

5) Since metal carbonate and metal bicarbonate are basic, they react with acids to give salt and water with the liberation of (NO2, SO2, and CO2).

Ans: CO₂

Metal carbonate and metal bicarbonate are bases which reacts with acids to give corresponding metal salts, water with the liberation of CO₂.

6) The hydrated salt of copper sulphate has color (red, white, blue).

Ans: blue

Because, the hydrated salt of copper sulphate is blue in color.

Answer briefly.

1) Classify the various types of Acids based on their sources.

Ans: According to Arrhenius theory, an acid is a substance which produces H⁺ or H₃O⁺ ions when dissolved in aqueous solution.

For example: when HCl is dissolved in water it produces H⁺ and Cl^– ions.

All acids contains essentially one or more hydrogen atoms but all substances containing hydrogen atoms are not always acids. For example: CH₄ and NH₃ contains hydrogen atoms but they are not acids.

Acids are classified on the basis of their sources as follows:

• Organic acids: Acids present in living things that is in plants and animals is called as organic acid. For example: HCOOH, CH₃COOH.
• Inorganic acids: Acids prepared from rocks and minerals are called as inorganic acids or mineral acids. For example: HCl, HNO₃, H₂SO₄.

2) Write any four uses of acids.

Ans: Acids are the substances which produces H⁺ ions when dissolved in aqueous solution are called as acids.

There lots of uses of acids in daily life also which are as follows.

• Hydrochloric acid is used as cleansing agent in toilets.
• Citric acid is used as food preservative and it is also used in the preparation of effervescent salts.
• Nitric acid is used in the manufacture of drugs, dyes, paints and fertilizers.
• Oxalic acid is used as bleach for wood and for removing black stains. It is also used to clean iron and manganese deposits from quartz crystals.
• Carbonic acid is used in aerated drinks.
• Tartaric acid is a constituent for baking powder.
• Sulphuric acid is called the king of chemicals because it is used in the preparation of many compounds. It is also used in car batteries also.

3) Give the significance of pH of soil in agriculture.

Ans: The pH of the soil decides the acidity and basicity of the soil. In case of soil, the pH is measured in the slurry of soil mixed with water. And lies between 3 to 10, with 7 as neutral. If the pH of soil is below 7 then it must be acidic and if pH of soil is above 7 then it must be basic. The pH of soil affects the plant nutrient availability. To increase the crop yield we have check yearly the pH of soil. Because the different crops required different types of minerals, nutrients and chemicals which are provided to them through soil only. Thus, the crop yield and soil are mainly depends on the pH values. Thus, in order to maintain the growth and productivity of crops, the pH of soil plays an important role in this. Hence, pH of soil in agriculture has most significance.

4) What are the various uses of Aquaregia?

Ans:  We all know that metals like gold and silver are not reactive with HCl and HNO₃. But the mixture of HCl and HNO₃ dissolve gold. This mixture is called as Aquaregia. In Aquaregia the proportion of HCl and HNO₃ is in the 3:1 ratio. It is yellow-orange fuming liquid and highly corrosive and also able to attack on gold and another substances.

There are many uses of Aquaregia which are as given below:

• It is used chiefly to dissolve metals such as gold and platinum.
• It also used for cleaning and refining gold

5) What are the uses of Plaster of Paris?

Ans:

• Salts are the products formed in the reaction of acids and bases. Salts produces positive and negative ions when dissolved in water.
• Plaster of Paris which is named as Calcium Sulphate Hemihydrate is the example of salt.
• It has chemical composition as CaSO₄.1/2 H₂
• It is used for plastering bones.
• And also used for making casts for statue.

6) Two acids ‘A’ and ‘B’ are given. Acid A gives one hydrogen ion per molecule of the acid in solution. Acid B gives two hydrogen ions per molecule of the acid in solution.

Ans:  Find out acid A and acid B:

• The acid A is the HCl, which gives one hydrogen ion per molecule of the acid in solution.
• And acid B is the H₂SO₄, which gives the two hydrogen ions per molecule of the acid in solution.

Which acid is called the King of Chemicals?

Sulphuric acid i.e. H₂SO₄   which is called as King of chemicals because it is used in the preparation of many other compounds. And also used in car batteries.

7) Define aquaregia.

Ans: We all know that metals like gold and silver are not reactive with HCl and HNO₃. But the mixture of HCl and HNO₃ dissolve gold. This mixture is called as Aquaregia. In Aquaregia the proportion of HCl and HNO₃ is in the 3:1 ratio. It is yellow-orange fuming liquid and highly corrosive and also able to attack on gold and another substances.

Correct the mistakes:

Ans:

a) Washing soda is used for making cakes and bread soft, spongy.

Baking soda is used in making baking powder.

And baking powder is the mixture of baking soda and tartaric acid.

Thus, baking powder is used for making cakes and breads soft and spongy.

b) Calcium sulphate hemihydrate is used in textile industry for bleaching cloths.

Bleaching powder i.e. calcium oxychloride CaOCl₂ is used in textile industry for bleaching cloths

9) What is neutralization reaction? Give an example.

Ans: According to Arrhenius theory, acids are the substances which are dissolved in aqueous solution produces H⁺ ions. And bases are the substances which dissolved in aqueous solution produces hydroxyl OH^– ions. When acids and bases react together then salt and water is produced. This reaction is called as neutralization reaction. The best example for neutralization reaction is reaction of HCl and NaOH. When HCl reacts with NaOH, HCl produces H⁺ and Cl^– ions and NaOH produces Na⁺ and OH^– ions. Thus HCl acts as acid and NaOH acts as a base. Na⁺ and Cl^– combines together to form salt and remaining byproduct is the water. This is called as neutralization reaction.

III. Answer in detail.

1) Differentiate hydrous and anhydrous salts with examples.

Ans: Hydrous Compounds;

• Hydrous compounds are those compounds which contains water molecule as a constituent in their structure.
• It describes the presence of water in compound and called as hydrates.
• Examples: ethanol, Copper (II) sulphate, Calcium sulphate, Barium chloride etc.

Anhydrous Compounds:

• Anhydrous compounds are those which does not contains water molecule as a constituent in their structure.
• It describes absence of water in the compound and called as anhydrates.
• Examples: Chromium chloride, Calcium (III) chloride etc.

2) Give the tests to identify Acids and Bases.

Ans: Acids are the substances which produces H+ ions when dissolved in aqueous solution whereas bases are the substances which produces OH- ions when dissolved in aqueous solution.

There are three types of tests to identify the acids and bases which are as follows:

Test with a litmus paper:

If a substance turns blue litmus paper into red, then it is termed as acid. And if the substance turns red litmus paper into blue then it is termed as base.

Test with the indicator Phenolphthalein:

If we add Phenolphthalein in a substance and if it turns colorless then that substance is the acid. And if we add Phenolphthalein in the substance and if Phenolphthalein get pink in color then that substance is called as base.

Test with an indicator Methyl orange:

In acid medium Methyl orange is pink in color and in basic medium Methyl orange is yellow in color.

In this by these three methods we can identify the tests of acids and bases easily.

3) Write any four uses of bases.

Ans: Bases are the substances which produces OH- ions when dissolved in aqueous solution.

There are many uses of bases in daily life also which are as follows:

• Sodium hydroxide is used in the manufacture of soaps.
• Calcium hydroxide is used in the white washing of buildings.
• Magnesium hydroxide is used as medicine for stomach disorders.
• Ammonium hydroxide is used to remove grease stains from cloths.

4) Write any five uses of salts.

Ans:

Salts are the products formed in the reaction of acids and bases. And they produces positive and negative ions when dissolved in water. There are four types of salts namely Acids salts, normal salts, basic salts and double salts.

There are many uses of salts in daily life also which are as below:

• The common salt NaCl is used in our food daily and also used as preservative.
• Washing soda i.e. sodium carbonate is used in softening hard water. And also used in glass, soap and paper industries.
• Baking soda i.e. sodium bicarbonate which is used in making baking powder which is the mixture of baking soda and tartaric acid.
• Baking soda is used to make cakes and breads, soft and spongy.
• Also baking powder neutralizes the acid in stomach and give relief.
• Bleaching powder i.e. calcium oxychloride is used as disinfectant and also used in textile industry for bleaching cotton and linen.
• Plaster of Paris i.e. Calcium Sulphate Hemihydrate is used for plastering bones and for making casts for statue.

5) Sulphuric acid is called King of Chemicals. Why is it called so?

Ans: According to Arrhenius theory, acids are the substances, when dissolved in aqueous solution produces H+ ions. They are sour to taste. Their aqueous solution conducts electricity since they have ions in them. Best example of acid is Sulphuric acid i.e. H₂SO₄  which is called as King of chemicals because it is used in the preparation of many other compounds. And also used in car batteries.

 

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