CHAPTER1CHEMFINALWITHPYQS notes-1.pptx helllo heloohshshsjs hsjsjs hsjsjsj

Bshshsjshehehehehdjdjdjsje rhdhxuke ehdheidke hdjdjdjd

1. A process in which new chemical (s) are formed Hydrogen gas react with oxygen gas to produce water under some condition CHEMICAL REACTION

2. Simple representation of a chemical reaction with symbols and formula. Hydrogen gas reacts with oxygen gas to produce water under some conditions CHEMICAL EQUATION H 2 (g) + 2 (g) — -------- > Reactants H 2 O (l) Products

3. F E C T S Evolution of a gas Formation of precipitate Colour change Temperature change State change

4. Number of Atoms of each element in a chemical equation Should be the same on LHS & RHS BALANCED CHEMICAL EQUATIONS A 2 (g) + B 2 (g) -------- > AB (g) Why Balance ?? Conservation of mass – total mass of reactants should be equal to total mass of products

5. Ultra pro practice - Metals Zn , Fe , Na , Al , Mg , Mn , Cu , Ca , Pb , Ba Cl , Br , S , N , C Non - Metals O H 2. Fe + H ₂ O — ------ > Fe ₃ O ₄ + H ₂ 1. Zn + HCL — ----- > Zncl 2 + H 2

6. + Al ₂ (SO ₄ ) ₃ --------- > BaSO ₄ + AlCl ₃ 4. BaCl ₂ ------- > PbO + NO ₂ + O ₂ 5. Pb(NO ₃ ) ₂ 3. Fe ₂ O ₃ + Al — ------- > Al ₂ O ₃ + Fe

7. Q. To balance the following chemical equation the values of x and y should respectively be a Al 2 O 3 + b HCl c AlCL 3 + d H 2 O Q. In order to balance the below chemical equation the value of x, y and z respectively are MnO 2 + x HCl (CBSE 2020) 2NaOH + x Al 2 O 3 y NaAlO 2 + H 2 O Q. To balance the chemical Equation find a,b,c,d (CBSE 2024) (CBSE 2023) MnCl 2 + y H 2 + z Cl 2

8. Combination Reaction Two or More reactant combine to form a single product TYPES OF CHEMICAL REACTION A + B P + Q + R AB X

9. Mg(s) + O 2 (g) (i) Mg burns with Dazzling white flame (Very bright light) A white MgO powder in watch glass Heat energy releases so temperature increases Combination & Exothermic Reaction ACTIVITY 1.1 MgO(s) + Heat (White )

10. Q.1 Why do we rub magnesium with sandpaper? Ans. To remove any layer of magnesium oxide already present on magnesium ribbon. Q.2 Why to keep magnesium ribbon away from your eyes? Ans. Because the reaction is exothermic & it emits dazzling white light so bright that you cannot see for a short time after looking at it . Q. A metal ribbon X burns in oxygen with a dazzling white flame forming a white ash Y. The correct description of X, Y and the type of reaction are. X = Ca ; Y = CaO, Type of reaction = Decomposition X = Mg ; Y = MgO, Type of reaction = Combination X = Al ; Y = Al2O, Type of reaction = Thermal decomposition X = Zn ; Y = ZnO, Type of reaction = Endothermic (CBSE 2023)

11. CaO(s) + H 2 O(l ) Imp Points Rise in temperature (exothermic) Quick lime reacts vigorously with water Water added slowly because reaction is exothermic (iv) Combination & Exothermic Reaction (v) Quicklime used in making cement (Quick lime) Ca(OH) 2 (aq) + Heat (Slaked lime) ACTIVITY 1.4

12. Q. The balanced chemical equation showing reaction between quicklime and water is (CBSE 2023) (a) 2CaO + H2O ------------------ > 2CaOH + H2 + Heat (b) CaO + H2O ------------------ > Ca(OH)2 + H2 + Heat (c) CaO + H2O ------------------ > Ca(OH)2 + Heat (d) 2CaO + 3H2O ------------------ > 2Ca(OH)3 + O2 + Heat White Wash Wall

13. OTHER EXAMPLES OF COMBINATION REACTION Burning of Coal C(s) + O 2 (g) -------- > CO 2 (g) Formation of water from H 2 (g) and O 2 (g) H 2 (g) + O 2 (g) -------- > H 2 O(l)

14. DECOMPOSITION REACTION Reverse of combination ; one reactant breaks into 2 or more products AB ------ > A + B H E A T (Thermal) E L E C T R I C I TY (Electrochemical) LIGHT (Photo chemical) DECOMPOSITION

15. Heat CaCO 3 (s) (Limestone) CaO(s) + CO 2 (g) Quick Lime Used in making cement

16. THERMAL DECOMPOSITION - Thermolysis Heat FeSO 4 (s) Ferrous sulphate Fe 2 O 3 (s) + SO 2 (g) + SO 3 (g) Ferric oxide Imp Points ACTIVITY 1.5 Green Dirty White Brown & acidic in nature Thermal Decomposition & Endothermic Reaction

17. Hea t Pb(NO 3 ) 2 (s) Lead nitrate (white ) PbO(s) + Lead Oxide (yellow) Imp Points I. Cracking sound NO 2 (g) – irritating II. Brown fumes smell Yellow solid residue PbO(s) NO 2 gas is acidic in nature & turns Heating of lead Nitrate and emission of nitrogen dioxide A paris of tongs Boiling Tube Lead nitrate Burner ACTIVITY 1.6 NO 2 (g) + O 2 (g ) Brown fumes moist blue litimus red Thermal Decomposition & Endothermic Reaction

18. Q. The products obtained when lead nitrate is heated in a boiling Q. The emission of brown fumes in the given experimental setup is due to: (CBSE 2023) tube are: (a) PbO,N 2 O and O 2 (c) Pb(NO 2 ) 2 and O 2 (b) NO, PbO and O 2 (d) NO 2 , PbO and O 2 (CBSE 2024)

19. Electric Current ELECTROLYTIC DECEMPOSITION / ELECTROLYSIS H 2 O(l) H 2 (g) + O 2 (g) ACTIVITY 1.7

20. (ii) Burning candle near H 2 (g) O 2 (g) Pop sound & candle extinguish Combustible but not supporter of combustion Candle burns more brightly Not Combustible but supporter of combustion (iii) Pure water is poor conductor of electricity so a few drop of acids is added, which acts as electrolyte & conducts electricity (i) Volume of gas H 2 : O 2 = 2 : 1

21. Sunlight PHOTOCHEMICAL DECOMPOSITION / Photolysis AgBr(s) Ag(s) + Br 2 (g) Sunlight ACTIVITY 1.8 AgCl(s) (White) Ag(s) + Cl 2 (g) (Grey) This is why AgCl & AgBr are kept in Black colour bottles to protect from sulight (used in black and white Photography ) Sunlight AgCl(s) (White)

22. Q. Select the following a decomposition reaction in which source of energy for decomposition is light: 2FeSO 4 ------- >Fe 2 O 3 + SO 2 + SO 3 2H 2 O ------- > 2H 2 + O 2 (C) 2AgBr ------- > 2Ag + Br 2 (d) CaCO 3 ------- > CaO +CO 2 Q. What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved: (CBSE 2024) (CBSE 2023)

23. Q. Silver chloride kept in a china dish turns grey in sunlight A. Write the colour of silver when it was kept in the china dish Name the type of chemical reaction taking place and write the chemical equation for the reaction State one use of reaction . Name one more chemical which can be used for the same purpose (CBSE 2023)

24. DISPLACEMENT REACTION: More reactive element replaces a less reactive element from its compound A + BC AC + B REACTIVITY SERIES

25. Zn(s) + H 2 SO 4 (aq) Zn(s) + CuSO 4 (aq) Pb(s) + CuSO 4 (aq)

26. Zn(s) + H 2 SO 4 (aq) OBSERVATIONS ( i) H 2 gas is colorless & odorless, burn with pop sand & extinguishes burning candle Temp increases, reaction is highly exothermic Dilute acid is used as reaction is highly exothermic and conc acid can lead to more exothermic and dangerous reaction Cork Glass Tube Conical Flask Dilute Sulphuric Acid Zinc granules ACTIVITY 1.3

27. Q. Study the diagram given below and identify the gas formed in the reaction (CBSE 2022) Carbon dioxide which extinguishes the burning candle Oxygen due to which the candle burns more brightly Sulphur dioxide which produces a suffocating smell Hydrogen which while burning produces a popping sound

28. DOUBLE DISPLACEMENT REACTION Exchange of ions between reactants A + B – + C + D – AD + BC Na 2 SO 4 (aq) + BaCl 2 (aq) Colourless Colourless BaSO 4 (s) + NaCl(aq) white ppt

29. Test tube Containing solution of sodium sulphate Test tube Containing solution of barium chloride ACTIVITY 1.10 (ii) OBSERVATIONS (i) White insoluble substance (precipitate) of BaSO 4 is formed. Double Displacement & precipitation reaction . Precipitation Reaction – When two aqueous soluble soluble solutions react to form a semi soluble / insoluble salt , the salt is called precipitate & such reaction is called precipitation reaction

30. Lead nitrate(aq) + Potassium iodide(aq) Pb(NO 3 ) 2 (aq) + KI(aq) PbI 2 + KNO 3 Colourless Colourless Yellow ppt ( Insoluble in water) Yellow insoluble substance (precipitate) of PbI 2 is formed. Double Displacement & precipitation reaction .

31. Q. When potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed What is the colour of this precipitate? Name the compound precipitated. Write the balanced chemical equation for this reaction. (iii) List two types of reactions in which this reaction can be placed. (CBSE 2019)

32. C 6 H 12 O 6 HEAT in REACTIONS C + Heat A + B EXAMPLES: 1. Respiration Glucose CO 2 (g) + H 2 0(l) + Energy Carbohydrates Glucose + Oxygen C 6 H 12 O 6

33. 2. Burning Of Natural Gas : CH 4 (g) + O 2 (g) CO 2 (g) + H 2 O(g) + Heat 3. Decomposition of vegetable into compost

34. EXAMPLES: Decomposition of: FeSO 4 Crystal CaCO 3 (s) Pb(NO 3 ) 2 (s) Heat A - - H - e - at - > B + C AgCl (s) AgBr (s) H 2 O(I) FeSO 4 - H e - a - t - > CaCO 3 - H - e - a - t > Pb(NO 3 ) 2 - H - e a - t - > AgCl ---- > AgBr - H - e - a - t > H 2 O - H - e - a - t >

35. Q. Select endothermic reaction from the following: (CBSE 2023) Decomposition of vegetable matter into compost. Decomposition of calcium carbonate to form quick lime and carbon dioxide. Burning of a candle. Process of respiration.

36. OXIDATION & REDUCTION Oxidation: If a chemical (A ) Gains oxygen Loses Hydrogen It is called oxidation of A. A is said to be oxidised. Reduction: If a chemical (B) Gains Hydrogen Loses Oxygen It is called reduction of B. B is said to be reduced.

37. Q. MnO 2 + 4HCl MnCl 2 + 2H 2 O + Cl 2 (CBSE 2024) MnO 2 is oxidised and HCL is reduced. HCl is oxidised. MnO 2 is reduced. MnO 2 is reduced and HCl is oxidised

38. Q. Which of the following statements about the reaction given below are correct? (CBSE 2022) MnO 2 + 4HCl MnCl 2 + 2H 2 O + Cl 2 HCL is oxidised to Cl 2 MnO 2 is reduced to MnCl 2 MnCl 2 , acts as an oxidizing agent HCl acts as an oxidizing agent (a) (ii), (iii) and (iv) (c) (i) and (ii) only (b) (i), (ii) and (iii) (d) (iii) and (iv) only

39. OBSERVATIONS Reddish/Brownish copper metal changes to black colour CuO(s) If H 2 (g) is passed over CuO, black colour changes to brown. Heat CuO(s) + H 2 (g) Cu(s) + H 2 O Heat ACTIVITY 1.11 CuO(s) Black colour Oxidation Of Copper Cu(s) + O 2 (g) Reddish/Brownish

40. Iron Hydrated (Reddish Brown) Iron oxide (Rust ) Corrosion : When a metal is attacked by substances around it such as moisture ( water vapour + oxygen ) , acid etc., it is said to corrode and this process is called corrosion . Examples - 1) Rusting of Iron

41. . 2) Tarnishing of copper 3) Tarnishing of silver NOTE : CORROSION is an example of Oxidation PREVENTION OF CORROSION CHAPTER 3

42. Rancidity: The taste or smell of food material containing fat/oil changes when it is left exposed to air for a long time. Oxidation Of Fat / Oil present in food material causes Rancidity Prevention: Antioxidants Air tight container Bag of chips (Flushed with Nitrogen gas)

43. CHEMICAL CHANGE A chemical reaction happened. Shape, size, color , etc. may also change. New chemicals are formed. Burning Of Paper Fermentation of grapes Souring Of Milk Curd from milk is left in a room during summer Rusting of iron Food Digestion Food Cooking Respiration Chemical Battery Usage Baking a cake

44. No chemical reaction happens. Shape, size, state , etc. may change. No new chemical is formed. PHYSICAL CHANGE Boiling water from the evaporating dish Melting of ice to give water Melting of wax Crushing a paper cup Crystallization