Latest Updated CBSE Class 10 Science CH-01 Chemical Reactions and Equations

CBSE Class 10 Science Notes Chapter 1 Chemical Reactions and Equations

Here are the key study points for the "Chemical Reactions and Equations" chapter from Class 10 Chemistry:

Definition: A process in which one or more substances (reactants) are transformed into new substances (products).
Indicators of a Reaction:
- Change in state
- Change in color
- Evolution of a gas
- Change in temperature or formation of a precipitate

Steps:
1. Write the skeleton equation.
2. Balance the elements individually, ensuring equal numbers of atoms on both sides of the equation.
3. Verify the final equation.

Example: Unbalanced: $H_2 + O_2 → H_2O$
Balanced: $2H_2 + O_2 → 2H_2O$

Combination Reaction: Two or more reactants combine to form a single product.
Example: $2Mg + O_2 → 2MgO$
Decomposition Reaction: A single compound breaks down into two or more substances.
Example: $2H_2O → 2H_2 + O_2$
Displacement Reaction: One element replaces another in a compound.
Example: $Zn + CuSO_4 → ZnSO_4 + Cu$
Double Displacement Reaction: Exchange of ions between two reactants.
Example: $NaCl + AgNO_3 → NaNO_3 + AgCl$
Redox Reaction: Involves oxidation (loss of electrons) and reduction (gain of electrons).

Corrosion: Rusting of iron due to exposure to air and moisture. Preventive methods include painting and galvanization.
Rancidity: Oxidation of fats and oils in food, prevented by storing food in airtight containers or adding antioxidants.

Balancing Equations: Write and balance given equations, identify reaction types, and predict response products.
Example MCQs:
- Which gas is used to store fat-containing foods?
  Answer: Nitrogen
- Identify reducing agents in $H_2S + I_2 → 2HI + S$ :
  Answer: $H_2S$

Question: Balance the following chemical equations:

Tip: Balancing chemical equations is crucial, as it aligns with the law of conservation of mass

Here are multiple-choice questions (MCQs) from Chapter 1: Chemical Reactions and Equations, Class 10 Science, based on the key concepts:

(a) It melts to form calcium oxide.
(b) It decomposes to form calcium oxide and carbon dioxide.
(c) It reacts with water to form calcium hydroxide.
(d) It reacts with oxygen to form calcium hydroxide.
Answer: (b) It decomposes to form calcium oxide and carbon dioxide.
$CaCO_3 → CaO + CO_2$

$2KClO_3 → 2KCl + 3O_2$

(a) Copper and ferrous sulfate
(b) Iron sulfate and copper oxide
(c) Ferrous sulfate and oxygen
(d) Copper and iron oxide
Answer: (a) Copper and ferrous sulfate
$Fe + CuSO_4 → FeSO_4 + Cu$

(a) Decomposition of calcium carbonate
(b) Dissolution of ammonium chloride in water
(c) Reaction of calcium oxide with water
(d) Electrolysis of water
Answer: (c) Reaction of calcium oxide with water
$CaO + H_2O → Ca(OH)_2 + Heat$

(a) Gas
(b) Precipitate
(c) Decomposition product
(d) Combustion product
Answer: (b) Precipitate
$AgNO_3 + NaCl → AgCl + NaNO_3$

(a) $CuO + H_2 → Cu + H_2O$
(b) $2AgNO_3 → 2Ag + 2NO_2 + O_2$
(c) $NaOH + HCl → NaCl + H_2O$
(d) $FeSO_4 → Fe_2O_3 + SO_2 + SO_3$
Answer: (a) $CuO + H_2 → Cu + H_2O$