Acids Bases and Salts Notes || Class 10 Chapter 2 Science ||
Chapter 2, Class 10
ACIDS, BASES AND SALTS
1. Those substances which has sour (खट्टा) taste, is called acids.
2. The chemical nature of such substances is acidic.
3. The acids present in plant materials and animals are called organic acids.
4. Organic acids (or naturally occurring acids) are weak acids.
5. E.g. Curd, lemon juice, orange juice and vinegar (सिरका) taste sour, it means acidic in nature.
Important name of the Organic acids
1. Acetic acid contains in vinegar
2. Formic acid (Methanoic acid) in Ant’s sting (डंक मारना), Nettle sting
3. Citric acid – Citrus fruits such as oranges, lemons, etc.
4. Lactic acid in Curd (दही)
5. Oxalic acid in Spinach (पालक), tomatoes
6. Ascorbic acid (Vitamin C) in Amla, Citrus fruits
1. The acids prepared from the minerals of the earth are called mineral acids.
2. Mineral acids are manmade acids.
3. The three most common mineral acids are: Hydrochloric acid (used in dye-stuffs (रंगनेवाला पदार्थ), textile, food and leather industries), Sulphuric acid (used in fertilisers (खाद), paints, dyes, chemicals, detergents, explosives (बारूद) and car batteries) and Nitric acid (used in fertilisers, explosives (like TNT: Tri-Nitro Toluene), dyes and plastics).
4. All the mineral acids are strong acids.
5. Only one mineral acid, carbonic acid, is a weak acid.
Concentrated and Dilute Acids
1. A concentrated acid is one which contains the minimum possible amount of water in it.
2. The concentration of an acid is decreased by adding more water to it.
3. When water is added to a concentrated acid, then a dilute acid is formed.
4. Thus, a dilute acid is one which contains much more of water in it.
Properties of Acids
1. Acids have a sour taste
2. Acids turn blue litmus to red
3. Acid solutions (acid is dissolved in water) conduct electricity (They are electrolytes)
4. Acids react with metals to form hydrogen gas – When an acid reacts with a metal, then a salt and hydrogen gas are formed. i.e.
Metal + Acid → Salt + Hydrogen gas
E.g. when dilute Sulphuric acid reacts with zinc metal, then zinc sulphate and hydrogen gas are formed:
Zn (s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)
Zinc (metal) (Sulphuric acid – Dilute) (Zinc sulphate – salt) Hydrogen
In this reaction, zinc metal displaces hydrogen from sulphuric acid. And this hydrogen is evolved as hydrogen gas. Most of the acids react with metals to form salts and evolve hydrogen gas. This shows that hydrogen is common to all acids.
5. Acids react with metal carbonates (and metal hydrogen carbonates) to form carbon dioxide gas
Metal carbonate + Acid → Salt + Carbon dioxide + Water
Metal hydrogen carbonate + Acid → Salt + Carbon dioxide + Water
E.g. (i) When dilute hydrochloric acid reacts with sodium carbonate, then sodium chloride, carbon dioxide and water are formed:
Na2CO3 (s) + 2HCl (aq) → 2NaCl (aq) + CO2 (g) + H2O (l)
Sodium carbonate Hydrochloric acid Sodium chloride Carbon dioxide Water
(ii) When dilute hydrochloric acid reacts with sodium hydrogen carbonate, then sodium chloride, carbon dioxide and water are formed:
NaHCO3 (s) + HCl (aq) → NaCl (aq) + CO2 (g) + H2O (l)
Sodium hydrogen- Hydrochloric acid Sodium chloride Carbon Water
On passing the carbon dioxide gas evolved through lime water,
When carbon dioxide gas is passed through lime water, the lime water turns milky due to the formation of a white precipitate of calcium carbonate
Ca (OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)
Calcium hydroxide Carbon dioxide Calcium carbonate Water
(Lime water) (White ppt.)
(Makes lime water milky)
6. Acids react with bases (or alkalis) to form salt and water
When an acid reacts with a base, then a salt and water are formed. That is
Acid + Base → Salt + Water
Actually, when an acid is treated with a base, the base neutralises the acid and destroys its acidity. Since an acid and a base neutralise each other’s effect, so the reaction between an acid and a base to form salt and water is called a neutralisation reaction.
E.g. NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)
Sodium hydroxide Hydrochloric acid Sodium chloride Water
(Base) (Acid) (Salt)
When hydrochloric acid reacts with sodium hydroxide solution, then a neutralisation reaction takes place to form sodium chloride and water
7. Acids react with metal oxides to form salt and water
Acids react with metal oxides to form salt and water
Metal oxide + Acid → Salt + Water
Copper (II) oxide is a metal oxide. Dilute hydrochloric acid reacts with copper (II) oxide to form copper (II) chloride and water
CuO (s) + 2HCl (aq) → CuCl2 (aq) + H2O (l)
Copper (II) oxide Hydrochloric acid Copper (II) chloride Water
WHAT DO ALL ACIDS HAVE IN COMMON
An acid is a substance which dissociates (अलग करना) (or ionises) on dissolving in water to produce hydrogen ions [H+ (aq) ions]
E.g. an aqueous solution of hydrochloric acid dissociates (or ionises) to form hydrogen ions (along with chloride ions):
HCl (aq) → H+ (aq) + Cl– (aq)
Hydrochloric acid Hydrogen ions Chloride ions
Popular posts from this blog
India size and location with notes in hindi Class 9 Chapter 1 Geography Class – 9, Chapter – 1 INDIA – SIZE AND LOCATION LOCATION 1. India lying entirely in the Northern hemisphere 2. The main land extends ( फैलना ) between latitudes 8°4'N and 37°6'N and longitudes 68°7'E and 97°25'E. 3. The Tropic of Cancer (23° 30'N) divides the country into almost two equal parts. 4. The southeast part of India lays in the Andaman and Nicobar Island in Bay of Bengal. 5. The southwest part lays in Lakshadweep islands in the Arabian Sea. SIZE 1. The land mass of India has an area of 3.28 million square km. 2. India’s total area is 2.4 % of the total geographical area of the world. 3. India is the 7 th largest country of the world. 4. India has a land boundary of about 15,200 km. 5. The total length of the coast line of the mainland including Andaman and Nicobar and Lak
Democracy in the Contemporary world with notes in hindi || Class 9 Chapter 1 Politics || Chapter 1 Democracy in the Contemporary World TWO TALES OF DEMOCRACY 1. Salvador Allende was the President of Chile (in South America). 2. He gave the speech on the morning of 11 September 1973, when his government was overthrown ( तख्ता पलट देना ) by the military. 3. Allende was the founder ( संस्थापक ) leader of the Socialist Party of Chile. 4. He led ( नेतृत्व करना ) the “Popular Unity” coalition ( गठबंधन ) to victory in the presidential election in 1970. 5. After being elected the President, Allende had taken several policy decisions to help the poor and the workers. 6. These included reform ( सुधार ) of the educational system, free milk for children and redistribution of land to the landless farmers. 7. He stopped foreign companies to taking away ( ले जाना ) natural resources like copper from the country
The story of village palampur with notes (हिंदी में) || Class 9 Chapter 1 Economics || Chapter – 1 The Story of Village Palampur Organisation of Production The aim ( उद्देश्य ) of production ( उत्पादन ) is to produce the goods and services. There are four requirements ( आवश्यकता ) for production of goods and services. 1) Land – Land and other natural resources such as water, forests, minerals 2) Labour –Some production activities require highly educated workers to perform the necessary tasks & other activities require workers who can do physical work. 3) Physical capital - variety of inputs needs at every stage during production. It is of two types a) Fixed capital – It is used for the long period of time for the production e.g. Tools, machines, buildings b) Working capital - Production requires Raw materials ( कच्चा माल ) and money (always required to make payments and buy items). It helps in increase in the production. 4) Human capital – To g