CBSC Science

*Reactivity Series :-    Reactivity series of metals The Arrangement of elements according to their reactivity is called reactivity series. * Reaction Of Metals with water. Metal react with water to form metal hydroxide and hydrogen gas is released Metal +water ------->metal hydroxide +hydrogen gas Na (s)  + cold H2O (l) ------------>NaOH (aq)+H2(g) K (s) + cold H2O (l) ---------> KOH (aq) + H2 (g) Note:-  Some Metals react with cold water: Sodium and Potassium are the metals which reacts with cold water. * Metals reacts with hot water Some Metals react with hot water: Calcium and Magnesium are the metals which reacts with hot water. Ca (s) + hot H2O (l)  --------> Ca(OH)2 (aq) Mg(s) + hot H20 (l) ----------> Mg(OH)2 (aq) Note:-  Some react with steam:Metals like Iron, Zinc and Aluminium react with steam *when iron reacts with steam : Fe (s)+steam H2O(l)--------->Fe3O4(s) + H2 (g) Some elements don't reacts:- Elements bel...

I) Reactivity Series: -            The Arrangement of elements according to their reactivity is called reactivity series. II) Reaction Of Metals with water.          Metal react with water to form metal hydroxide and hydrogen gas is released Metal +water ------->metal hydroxide +hydrogen gas Na (s) + cold H2O (l) ------------>NaOH (aq)+H2(g) K (s) + cold H2O (l) ---------> KOH (aq) + H2 (g) ✓Some Metals react with cold water:  Sodium and Potassium are the metals which reacts with cold water. ✓Some Metals react with hot water:  Calcium and Magnesium are the metals which reacts with hot water. Ca (s) + hot H2O (l) --------> Ca(OH)2 (aq) Mg(s) + hot H20 (l) ----------> Mg(OH)2 (aq) ✓Some metals react with steam:        Metals like Iron, Zinc and Aluminium react with steam ✓when iron reacts with steam :  Fe (s)+steam H2O(l)--------->Fe3O4(s) +H2 (g) ✓Some elements don't reacts:-...

  Metals and Non- Metals full explaination Class 10 Science Chapter 3 - Metals and non metals Element: Is a substance that can’t be broken into more simpler substances. Elements are classified into different categories: -: Metals :- Metals Metals are those elements which have 1,2 or 3 valence electrons in their valence shell. Example : atomic no. of Na =11 Electronic confugration =2,8,1 They always loose electrons to form electropositive ions. Na – 1electron ------Na + :-  Non Metals :- Non-Metals -> Non metals are those elements which have 4,5,6 or 7 valence electrons in their valence shell and they always gain electrons to form electronegative ions. Cl(17) – 1 electron --------Cl- Electronic Configuration = 2,8,7 Video Explanation of Lesson Metals and Non-Metals II)  Physical Properties Of Metals and Non Metals 1. malleability: process of beating into thin sheets Metals :are malleable. Gold and silver is the most malleable metals. Malleability Non metals :non malle...

Acid-bases and salts * Preparation and uses of important compounds. I) Caustic Soda (Sodium Hydroxide, NaOH) Preparation of Sodium hydroxide Preparation: In the process of electrolytic decomposition of brine (aqueous solution of sodium chloride), brine decomposes to form sodium hydroxide. 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g) In this process, chlorine is moved towards anode and hydrogen gas is moved towards cathode as by products. This whole process is known as Chlor – Alkali process. Uses: Sodium hydroxide is used for degreasing of metals, manufacturing of paper, soap, detergents, artificial fibres, etc. II) Bleaching Powder (Calcium Oxychloride, CaOCl2) Preparation of Bleaching powder Preparation: Bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH)2]. Ca(OH)2 + Cl2→ CaOCl2 + H2O Uses: (i) It is use for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry; (i...

  • Importance of pH in everyday life :- --------------------------------------- I) Are plants and animals pH sensitive ?   -> Our body works within the pH range of 7.0 to 7.8 .  -> Organisms survive in this narrow pH range change.  -> When pH of rain water is less than 5.6 then it is called acid rain . It lowers the pH of river water when mix with it and the survival of aquatic life becomes difficult. II) pH of Soil :- pH of Soil   -> plants required a specific pH for their healthy growth.  -> In most plants, the optimum pH range is from 5.5 to 7.0 , but some plants will grow in more acid soil or may require a more alkaline level.   III) pH in our digestive system :- pH of digestive system   -> Our stomach produces hydrochloric acid which helps in the digestion of food without harming the stomach.   -> During indigestion stomach produces too much acid which causes pain and irritation . To get ride from thi...

 I) What happens to an Acid  in a Water Solution ? ->  The hydrogen ion produced in the presence of water in HCl. - >The separation of H+ ion from HCl molecules cannot occur in the absence of water.   HCl + H2O --------> H3O+  + Cl- - >Hydrogen ions cannot exist alone but exist after combines water molecules hence H+ (aq) or hydronium ion (H3O+) .   H+ + H2O --------> H3O+ II) What happens to an Base in a Water Solution ? - >Bases generate hydroxide (OH-) ions in water.  Bases which soluble in water are called alkalis .   Examples:-   a) NaOH(s) + H2O(l) --------> Na+(aq) + OH-(aq)  b) KOH(s) + H2O (l) ----------> K+ (aq) + OH- (aq)  c)  Mg(OH)2 (s) + H2O (l) ----------> Mg2+(aq) +2OH- (aq) III) Process of mixing of Acid or a Base with Water. - >The process of dissolving an acid or a base in water is a exothermic process .  - >We must take care when doing this process. Like mixing of c...

  I) Acids and Bases reacts with each other. - > When Acids reacts with Bases to form Salt and water as product. This reaction is also called as neutralisation reaction . Acid + Base ---------> Salt + Water  Example:- i) NaOH (aq) + HCl (aq) ---------> NaCl (aq) + H2O(l) ii) MgOH (aq) + HCl (aq) -------> Mg(OH)2 (aq) + H2O (l) iii) LiOH (aq) + HCl (aq) ---------> LiCl (aq) + H2O (l) iv) Ca(OH)2 (aq) + H2SO4 (aq) ---------> CaSO4 (aq) + H2O (l) II) Metallic Oxides reacts with Acids:- - > When Metallic Oxides reacts with Acids it gives Salt and Water as products. Metallic Oxide + Acid ------> Salt + Water Example :-  i)  CuO (s) + HCl (aq) -------> CuCl2 (aq) + H2O (aq) black colour                     blue-green colour ->We notice that tht the colour of the solution becomes blue-green due to the formation of copper(II) chloride in the reaction . ii) CuO (s) + H2SO4 (aq) -------> CuSO4 ...

                             • When Acids reacts with Metal.  ->  Acid + Metal ---------> Salt + Hydrogen gas. -> When Acids react with Metals it gives salt and liberate hydrogen gas. Example:- i) 2HCl (l)+ 2Na(s) ---------> 2NaCl(s)+ H2(g) ii) H2SO4 (l) + Mg (s) ----------> MgSO4(s) + H2 (g)  iii) 2CH3COOH (l) + 2Na(s) -------> 2CH3COONa (s) + H2 (g) • When Bases reacts with Metals: -> When bases reacts with metals it gives salt and Hydrogen gas . Base + Metal ---------> Salt + Hydrogen gas Example:-  I) 2NaOH (aq) + Zn (s) ----------> Na2ZnO2 (s) + H2 (s) II) NaOH (aq) + Al (s)  ----------> NaAlO2 + H2 (s) • Metal carbonate and metal hydrogen carbonate reacts with acids. -> When Metal carbonate/ Metal hydrogen carbonate reacts with acids to give Salt, Water and  releases Carbon dioxide gas. Metal carbonate/Metal hydrogen carbonate + Acid ------> ...