Chemistry Formulae
Essential formulae for CBSE Class 10 โข First 2 chapters FREE!
Chapter 1: Chemical Reactions and Equations
Balancing Chemical Equations
Reactants โ Products (Atoms conserved)
Law of Conservation of Mass: Total mass of reactants = Total mass of products. Number of atoms of each element must be e...
๐ก Example:
Unbalanced: Hโ + Oโ โ HโO
Step 1: Count atoms
Left: 2H, 2O | Right: 2H, 1O
Step 2: Balance...
Step 1: Count atoms
Left: 2H, 2O | Right: 2H, 1O
Step 2: Balance...
Combination Reaction
A + B โ AB (Two or more โ One)
Two or more substances combine to form a single product. Usually exothermic (releases heat). Examples: burning, quick li...
๐ก Example:
Examples:
1. CaO + HโO โ Ca(OH)โ + Heat
(Quick lime โ Slaked lime, whitewashing)
2. 2Mg...
1. CaO + HโO โ Ca(OH)โ + Heat
(Quick lime โ Slaked lime, whitewashing)
2. 2Mg...
Decomposition Reaction
AB โ A + B (One โ Two or more)
Single compound breaks into two or more simpler substances. Requires energy input: Thermal (heat), Electrolytic (electri...
๐ก Example:
Types:
1. Thermal Decomposition:
CaCOโ --heatโ CaO + COโ
2Pb(NOโ)โ --heatโ 2PbO + 4NO๏ฟฝ...
1. Thermal Decomposition:
CaCOโ --heatโ CaO + COโ
2Pb(NOโ)โ --heatโ 2PbO + 4NO๏ฟฝ...
Displacement Reaction
A + BC โ AC + B (More reactive displaces less reactive)
More reactive element displaces less reactive element from its compound. Based on Reactivity Series. Metal displaces met...
๐ก Example:
Examples:
1. Zn + CuSOโ โ ZnSOโ + Cu
(Zn more reactive than Cu)
Blue solution โ Color...
1. Zn + CuSOโ โ ZnSOโ + Cu
(Zn more reactive than Cu)
Blue solution โ Color...
Double Displacement Reaction
AB + CD โ AD + CB (Exchange of ions)
Two compounds exchange their ions to form two new compounds. Usually produces: precipitate (โ), gas (โ), or water. A...
๐ก Example:
Examples:
1. Precipitate Formation:
NaโSOโ + BaClโ โ BaSOโโ + 2NaCl
(White precipitate ...
1. Precipitate Formation:
NaโSOโ + BaClโ โ BaSOโโ + 2NaCl
(White precipitate ...
Oxidation
Gain of oxygen OR Loss of hydrogen OR Loss of electrons
Three ways to identify oxidation: (1) Element/compound gains oxygen (2) Compound loses hydrogen (3) Species loses electr...
๐ก Example:
Examples:
1. Gain of Oxygen:
2Cu + Oโ โ 2CuO
(Copper oxidized - gains oxygen)
2. Loss of Hydro...
1. Gain of Oxygen:
2Cu + Oโ โ 2CuO
(Copper oxidized - gains oxygen)
2. Loss of Hydro...
Reduction
Loss of oxygen OR Gain of hydrogen OR Gain of electrons
Opposite of oxidation: (1) Element/compound loses oxygen (2) Compound gains hydrogen (3) Species gains electrons. Oxidat...
๐ก Example:
Examples:
1. Loss of Oxygen:
CuO + Hโ โ Cu + HโO
(CuO reduced - loses oxygen)
2. Gain of Hyd...
1. Loss of Oxygen:
CuO + Hโ โ Cu + HโO
(CuO reduced - loses oxygen)
2. Gain of Hyd...
Redox Reaction
Oxidation and Reduction occur simultaneously
In every reaction where oxidation occurs, reduction must also occur (and vice versa). The substance that gets oxidized i...
๐ก Example:
Example 1: CuO + Hโ โ Cu + HโO
โข CuO โ Cu (Reduction: loses O)
CuO is oxidizing agent
๏ฟฝ...
โข CuO โ Cu (Reduction: loses O)
CuO is oxidizing agent
๏ฟฝ...
Corrosion
Metal + Oโ + HโO โ Metal oxide/hydroxide
Slow oxidation of metals by air, water, and other substances. Rusting of iron: Fe reacts with Oโ and HโO. Prevention...
๐ก Example:
Rusting of Iron:
4Fe + 3Oโ + xHโO โ 2FeโOโยทxHโO (Hydrated iron oxide)
Conditions neede...
4Fe + 3Oโ + xHโO โ 2FeโOโยทxHโO (Hydrated iron oxide)
Conditions neede...
Rancidity
Fats/Oils + Oโ โ Oxidized products (bad smell/taste)
Oxidation of fats and oils in food, making them smell and taste bad. Prevention: antioxidants, nitrogen packing, refrige...
๐ก Example:
Cause: Oxidation of unsaturated fatty acids in fats/oils
Prevention Methods:
1. Add antioxidants (B...
Prevention Methods:
1. Add antioxidants (B...
Chapter 2: Acids, Bases and Salts
pH Scale
pH = -logโโ[Hโบ] or [Hโบ] = 10โปแตแดด
Neutralization Reaction
Acid + Base โ Salt + Water
Acid + Metal Reaction
Acid + Metal โ Salt + Hydrogenโ
Acid + Metal Carbonate Reaction
Acid + Carbonate โ Salt + Water + COโโ
Chemistry Questions
Practice with CBSE pattern questions โข Free chapters unlocked!
Ch 1: Chemical Reactions and Equations
Q. Which of the following is an example of a decomposition reaction?
Ch 1: Chemical Reactions and Equations
Q. In the reaction Zn + CuSOโ โ ZnSOโ + Cu, zinc is:
Ch 1: Chemical Reactions and Equations
Q. The decomposition of silver chloride in presence of sunlight is:
Ch 1: Chemical Reactions and Equations
Q. Which gas is evolved when dilute HCl reacts with zinc?
Ch 1: Chemical Reactions and Equations
Q. What type of reaction is: CaO + HโO โ Ca(OH)โ?
Ch 1: Chemical Reactions and Equations
Q. What is a redox reaction? Give an example.
Ch 1: Chemical Reactions and Equations
Q.
Balance the following chemical equation:
Fe + HโO โ FeโOโ + Hโ
Ch 2: Acids, Bases and Salts
Q. The pH of a neutral solution is:
Ch 2: Acids, Bases and Salts
Q. Which of the following has pH less than 7?
Ch 2: Acids, Bases and Salts
Q. What happens when sodium carbonate reacts with hydrochloric acid?
Ch 2: Acids, Bases and Salts
Q. Plaster of Paris is chemically:
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