NCERT Formulas Class 10 Science Chapter 1 Chemical Reactions and Equations

⚖️ Law of Conservation of Mass

Mass can neither be created nor destroyed in a chemical reaction. Total mass of reactants = Total mass of products.

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$$\text{Total Mass of Reactants} = \text{Total Mass of Products}$$ $$\sum \text{Atoms (Reactant side)} = \sum \text{Atoms (Product side)}$$

➕ Combination Reaction

When two or more reactants combine to form a single product.

$$A + B \rightarrow AB$$
Slaking of Lime: $$CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq) + \text{Heat}$$

💥 Decomposition Reactions

One reactant breaks down into simpler products using Heat ($\Delta$), Electricity, or Light ($hv$).

$$AB \xrightarrow{\text{Energy}} A + B$$
Thermal Decomposition (Lead Nitrate): $$2Pb(NO_3)_2(s) \xrightarrow{\Delta} 2PbO(s) + 4NO_2(g) + O_2(g)$$

🔄 Displacement Reaction

A more reactive element displaces a less reactive element from its compound solution.

$$Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)$$

[Image of iron nail in copper sulphate solution]

↔️ Double Displacement

Exchange of ions between two reactants. Results in the formation of a precipitate.

$$Na_2SO_4(aq) + BaCl_2(aq) \rightarrow BaSO_4(s)\downarrow + 2NaCl(aq)$$

🔥 Redox Reactions

Oxidation: Gain of Oxygen / Loss of Hydrogen.
Reduction: Loss of Oxygen / Gain of Hydrogen.

$$CuO + H_2 \xrightarrow{\Delta} Cu + H_2O$$

(HCl → Cl₂ = Oxidation | MnO₂ → MnCl₂ = Reduction)

🌡️ Energy Classification

Exothermic: Heat is released (Respiration).
Endothermic: Heat is absorbed (Photosynthesis).

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$$

🛡️ Corrosion and Rancidity

Corrosion: Degradation of metals due to moisture/acid (Rusting: $Fe_2O_3 \cdot xH_2O$).

Rancidity: Oxidation of fats and oils leading to bad smell/taste. (Prevention: Nitrogen gas, Antioxidants).