Class 10 Science - CBSE
Acids, Bases and Salts
The Class 10 CBSE chapter 'Acids, Bases and Salts' explores the chemical properties of substances based on their hydrogen ion concentration. Students learn about indicators, pH scale, neutralization reactions, and the industrial preparation of important compounds like sodium hydroxide, bleaching powder, baking soda, washing soda, and plaster of Paris. This chapter is exceptionally high-scoring and forms the foundation of inorganic chemistry. Board exams regularly feature questions on chemical equations, pH-based numericals, and the practical uses of salts. Mastering this chapter ensures confidence in answering both direct memory-based questions and tricky application-based scenarios in the CBSE science paper.
Start Learning FreeKey Concepts
Chemical Properties of Acids and Bases
Acids react with metals to release hydrogen gas and form salts, while bases react with certain metals like zinc to form hydrogen gas. Acids react with metal oxides to form salt and water, and bases react with non-metallic oxides similarly, showing their chemical nature.
Action of Acids and Bases in Water
Acids produce hydrogen ions (H+) or hydronium ions (H3O+) in the presence of water, which is responsible for their acidic properties. Bases generate hydroxide ions (OH-) in water, and those soluble in water are called alkalis.
The pH Scale
A quantitative measure of hydrogen ion concentration in a solution, ranging from 0 to 14. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic, playing a vital role in everyday life and agriculture.
Family of Salts
Salts are ionic compounds formed by the neutralization reaction between an acid and a base. Salts having the same positive or negative radicals are said to belong to the same family, such as sodium salts or chloride salts.
Chemicals from Common Salt
Common salt (sodium chloride) is a crucial raw material for various chemicals used in daily life and industry, including sodium hydroxide, bleaching powder, baking soda, washing soda, and plaster of Paris.
Important Formulas
Board Exam Info
In the CBSE Class 10 Science board exam, this chapter typically carries around 4 to 6 marks. Questions frequently include chemical equation balancing, identification of unknown compounds based on reactions, pH-based reasoning questions, and descriptive questions on the preparation and uses of salts like Plaster of Paris or Baking Soda.
Frequently Asked Questions
Why do dry HCl gas and dry acid not change the color of dry litmus paper?
Dry HCl gas does not dissociate to form hydrogen ions (H+) in the absence of water. Hydrogen ions are responsible for acidic behavior, so moisture is required to show acidity and change litmus color.
What happens when electricity is passed through an aqueous solution of sodium chloride (Brine)?
It undergoes chlor-alkali process, decomposing to form sodium hydroxide (alkali), chlorine gas (at the anode), and hydrogen gas (at the cathode).
Why should curd and sour substances not be kept in brass and copper vessels?
Curd and sour substances contain acids which react with the metals (brass and copper) to form toxic soluble salts that can cause food poisoning.
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