L-4 Chemical Reactions & Equations | Ch-1 Class 10 Science | CBSE | NCERT | Tarif Bhayana

In this lecture, Tarif Sir covers three major types of chemical reactions from Chapter 1 - Chemical Reactions and Equations for Class 10 Science. This is Lecture 4 of the series, picking up right after Combination Reactions covered in the previous session. What You'll Learn: Decomposition Reactions: definition and how they are the reverse of combination reactions Thermal Decomposition: heating of Lead Nitrate (Pb(NO3)2) producing PbO, NO2 (brown fumes), and O2; heating of Ferrous Sulphate (FeSO4) producing ferrous oxide (reddish brown), SO2 (match-burning smell), and SO3 Electrolysis of Water: complete setup explained - graphite electrodes, 6V battery, dilute H2SO4; H2 collected at cathode, O2 at anode; volume ratio of H2 to O2 is 2:1; how to test each gas (pop sound for H2, glowing splint for O2); why H2SO4 is added (pure water is a poor conductor) Photochemical Decomposition: decomposition of AgCl and AgBr by sunlight; why these silver salts are stored in dark coloured bottles; use of AgBr in black and white photography Lab Safety: correct technique for smelling gases (wafting), safe positioning of boiling tube mouth Displacement Reactions: definition, concept of Reactivity Series (Activity Series) of metals - K, Na, Ba, Ca, Mg, Al, Zn, Fe, Co, Ni, Sn, Pb, H, Cu, Hg, Ag, Au, Pt; mnemonic trick to remember the series; Zn + H2SO4 reaction; Fe nail in CuSO4 solution - colour changes explained Double Displacement Reactions: definition, partner exchange concept; Na2SO4 + BaCl2 reaction producing BaSO4 precipitate (white) and NaCl; connection to precipitation reactions Key colours of precipitates: BaSO4 (white), AgCl (white), PbI2 (yellow), CuS (black) Important concept: All decomposition reactions are endothermic This lecture is highly important for board exams. These topics - decomposition, displacement, and double displacement reactions - are asked every year in CBSE, RBSE, MPBSE, HPBSE, and UBSE board exams in the form of definitions, equations, colour identification, and activity-based questions. About the Teacher: Tarif Sir teaches at @TarifBhayana-9th10th - your go-to channel for Class 9 and Class 10 Science. Timestamps: 0:00 - Introduction and recap of previous lecture 1:28 - Decomposition Reactions: definition and concept 3:11 - Energy required for decomposition (heat, light, electricity) 4:17 - Thermal Decomposition: Heating of Lead Nitrate 9:28 - Thermal Decomposition: Heating of Ferrous Sulphate 12:24 - Electrolysis of Water: introduction 14:24 - Electrolysis of Water: setup and process 18:22 - Volume ratio of H2 and O2 (2:1) and reason 20:19 - How to test gases at cathode and anode 21:45 - Photochemical Decomposition: Silver Chloride 24:57 - Silver Bromide and Black and White Photography 26:02 - Why silver salts are stored in dark bottles 27:29 - Displacement Reactions: definition 29:22 - Reactivity Series (Activity Series) of Metals 33:14 - Displacement example: Zn + H2SO4 36:50 - Displacement example: Fe nail in CuSO4 solution 39:26 - Double Displacement Reactions: definition 40:44 - Double Displacement example: Na2SO4 + BaCl2 42:50 - Precipitate colours to remember 43:35 - Recap and summary Class 10 Science Chapter 1 | Chemical Reactions and Equations | Types of Chemical Reactions | Decomposition Reaction | Thermal Decomposition | Electrolysis of Water | Photochemical Decomposition | Displacement Reaction | Double Displacement Reaction | Activity Series of Metals | Reactivity Series | CBSE Class 10 | RBSE Class 10 | MPBSE Class 10 | Board Exam 2025-26 | Tarif Sir decomposition reaction class 10, displacement reaction class 10, double displacement reaction class 10, electrolysis of water class 10, thermal decomposition, photochemical decomposition, reactivity series of metals, activity series class 10, chemical reactions and equations, chapter 1 class 10 science, CBSE class 10 science, RBSE class 10 science, types of chemical reactions, Tarif Sir, class 10 board exam