Exploring the Chemistry of Acids, Bases and Salts in Future Classes
Acids, bases, and salts are important concepts in chemistry that can be studied in the classroom. CBSE notes and resources can be used to learn about these topics. Downloadable PDFs are available to help students understand and apply the concepts they are learning. Acids, bases, and salts are important for understanding the reactions that occur in the world around us. With the right resources, students can get a better understanding of these important concepts.
At our education website, you can easily download PDFs of CBSE Class 10 Science topics, such as Acids, Bases and Salts. These PDFs provide comprehensive definitions of important concepts related to Acids, Bases and Salts. With the help of these definitions, students can easily understand and remember the topics. Download our PDFs now and get the best learning experience
ACIDS BASES AND SALTS
ACIDS:
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These are the substances that have a sour taste.
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They turn blue litmus paper red.
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They give ions in aqueous solution.
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The term ‘acid’ has been derived from the Latin word, acidus, which means sour.
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Strong Acids (mineral acid): HCl (hydrochloric acid), H2SO4 (sulphuric acid), HNO3 (nitric acid)
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Weak Acids: acetic acid, Oxalic acid, Lactic acid, citric acid etc.
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Concentrated Acid: Having more amount of acid + less amount of water
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Dilute Acid: Having more amount of water + less amount of acid
BASES:
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These are the substances that are bitter in taste and soapy in touch.
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They turn red litmus paper blue.
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They give ions in aqueous solution.
Strong Bases: NaOH (sodium hydroxide), KOH (potassium hydroxide),
Weak Bases: Ca(OH)2(calcium hydroxide) etc.
Alkalis:
Water soluble base is called alkali.
CHEMICAL PROPERTIES OF ACIDS AND BASES
The reaction of Metals with Acids
The reaction of Metals with bases
Hydrogen gas released can be tested by bringing a burning candle near gas bubbles, it burst with a pop sound.
The reaction of Metal Carbonates/Metal Hydrogen Carbonates with Acids
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Carbon dioxide can be tested by passing it through lime water.
(Lime water turns milky.)
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When excess carbon dioxide is passed,
The reaction of Metal Carbonates/Metal Hydrogen Carbonates with bases
The reaction of Metallic Oxides with Acids
Metallic oxides are basic.
Example- (calcium oxide), (magnesium oxide) are basic oxides.
The reaction of Metallic Oxides with Acids
Non-metallic oxides are acidic.
Acid or Base in Water Solution
Acids produce H ions in presence of water.
Ions cannot exist alone, they exist as H3O (hydronium ions).
+
+
Bases when dissolved in water gives OH ions.
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Indicators
Indicators are the substance that change their colour or odour when added into an acid or alkaline solution. Indicators can be classified as natural, synthetic indicators, olfactory indicators and universal indicators.
Universal indicator:
To judge how strong a given acid or base is, a universal indicator is a mixture of several indicators. It shows different colours at different concentrations of ions in the solution.
Strength of Acid and Base
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Strength of an acid or base depends on the number of H+ ions or OH- ions produced by them respectively.
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Larger the number of H+ ions produced by an acid, stronger is the acid. Similarly, larger the number of the OH- ions produced by a base, stronger is the base.
pH Scale:
A scale for measuring H+ ion concentration in a solution. P in pH stands for potenz a German word that means power. It has values ranging from 0 (very acidic) TO 14 (very alkaline).
thus, pH is a number which indicate the acidic or basic nature of a solution.
pH of some common substances shown on a pH paper
pH of some common substances shown on a pH paper
Plants and animals are pH sensitive
Our body work normally within a pH range of 7.0 to 7.8. when pH of rain water goes below 5.6, it is called acid rain. It lowers the pH of the river water and makes survival of aquatic life difficult.
pH of the soil
Nature of soil is known by testing its pH and then a particular crop is grown in it by selecting fertilizer.
pH of our digestive system
During indigestion the stomach produces too much acid, it causes pain and irritation. To correct the disturbed PH range, milk of magnesia (Mg(OH)2 a mild base) is used as a medicine, which is also called antacid.
pH change leads to tooth decay
If the Ph inside the mouth decreases below 5.5 (acidic), the decay of tooth enamel begins. The bacteria present in the month degrades the sugar and left-over food particles and produce acids that remains in the mouth after eating.
To prevent tooth decay, toothpastes (basic) are used which neutralize the excess acid.
Self-defense by animal and plants through chemical warfare
When insect like honeybee, ant, etc., bite, they inject an acid into the skin, that causes pain and irritation. If a mild base like baking soda is applied on the affected area, it gives relief.
pH in plants
Stinging hair of nettle leaves injects methanoic acid in the skin which causes burning pain. It is cured by rubbing with leaves of dock plant.
Some naturally occurring acids
Salts
These are the compounds formed from the reaction of acid and base. example NaCl(sodium chloride), KCl(potassium chloride)
The reaction of Acids and Bases with Each Other
Neutralization Reaction:
The reaction of an acid with a base is called a neutralization reaction.
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Salt of strong acid and strong base are neutral (pH = 7). Salts of strong acid and weak base are acidic (pH < 7) and salts of strong base and weak acid are basic in nature (pH > 7).
Chemicals from Common Salt (NaCl)
Caustic soda or Sodium Hydroxide (NaOH):
When electricity is passed through an aqueous solution of NaCl (brine), it decomposes to form NaOH. (Chlor-alkali process)
At anode: Cl2 gas
At cathode: H2 gas
Near cathode: solution is formed.
Uses:
H2: Fuels, margarine
Cl2: Water treatment, PVC
soaps, and paper making
Bleaching Powder or calcium oxychloride (CaOCl2):
It is produced by the action of chlorine on dry slaked lime.
Uses:
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Bleaching cotton in the textile industry.
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Bleaching wood pulp in paper factories.
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The oxidizing agent in chemical industries.
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Disinfecting drinking water.
Baking Soda (Sodium Hydrogen Carbonate) (NaHCO3):
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When it is heated during cooking:
Uses:
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For making baking powder (a mixture of baking soda and tartaric acid). When baking powder is heated, CO2 is produced which causes bread and cake to rise to make them soft and spongy.
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An ingredient in antacid.
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Used in soda acids, fire extinguishers.
Washing Soda or sodium carbonate
Recrystallization of sodium carbonate gives washing soda.
Uses:
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In the glass, soap, and paper industry.
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Manufacture of sodium compounds such as borax.
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Cleaning agent for domestic purposes.
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For removing permanent hardness of the water.
Plaster of Paris (Calcium sulphate hemihydrates) (CaSO4.1/2H2O ):
On heating gypsum (CaSO4.2H2O) at 373K, it loses water molecules and becomes Plaster of Paris (POP).
On heating gypsum (CaSO4.1/2H2O) at 373K, it loses water molecules and becomes Plaster of Paris (POP).
Uses:
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Doctors use POP for supporting fractured bones.
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For making toys, material for decoration.
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For making surfaces smooth.
The water of Crystallization:
It is a fixed number of water molecules present in one formula unit of salt.
