CH-2 ACIDS,BASES &SALTS class 10 ncert.pptx

CH-2 ACIDS,BASES &SALTS class 10 ncert

1. CHAPTER 2 ACIDS BASES SALTS H +, OH - ,MX

2. SUB –CONCEPTS 2.1 UNDERSTANDING THE CHEMICAL PROPERTIES OF ACIDS AND BASES 2.2 WHAT DO ALL ACIDS AND ALL BASES HAVE IN COMMON? 2.3 HOW STRONG ARE ACID OR BASE SOLUTIONS? 2.4 MORE ABOUT SALTS

3. 2.1 UNDERSTANDING THE CHEMICAL PROPERTIES OF ACIDS AND BASES Acid Any substance that in water solution  tastes sour, changes the colour of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen , reacts with  bases to form  salts,and promotes certain chemical reactions (acid catalysis). e.g. HCl,HNO 3, H 2 SO 4 ……

4. BASE Bases are substances that in aqueous solution release hydroxide ions ,are slippery to the touch ,can taste bitter if an alkali, change the colour of indicators . e.g. NaOH , Ca(OH) 2, NH 4 OH,…

5. SALT Substance produced by the reaction between an acid and a base. It consists of the positive ion of a base and the negative ion of an acid. e.g. NaCl , KNO 3 , MgCl 2, CaSO 4 …….

6. 2.1.1 ACIDS and BASES in the laboratory ACTVITY 2.I SAMPLE solution Red litmus Blue litmus Phenolph-thlein Methyl orange HCL No change Turns red No change pink CH3COOH No change Turns red No change pink NaOH Turns blue No change crimson yellow NH 4 OH Turns blue No change crimson yellow

7. 2.1.2 OW DO A CIDS AND B ASES REACT WITH M ETALS

8. R eaction between Zn and dil. HCl and testing H 2 gas by burning HX +M MX+H 2 Zn(s)+2HCl ( dil ) ZnCl 2+ H 2 Observations : 1.Metals displace H 2 from dil acids 2.Metal +Acid residue gives salt 3.Cu,Hg,Ag,Au,Pt do not displace hydrogen because these are less reactive than Hydrogen 4.The gas liberated in the reaction burns with a pop sound 5.H 2 is highly combustible (it catches fire very easily)

9. ACTIVITY 2.4(VIFE) REACTON BETWEEN Zn and NaOH

10. Reaction between Zn and NaOH Zn + 2NaOH heat Na 2 ZnO 2 + H 2 Bluish white strong sol . Sodium zincate solid(colorless) 1. S uch reactions are not possible with all metals 2. U sed to treat or prevent low levels of zinc. 3 .Zn is needed for the body’s immune system to properly work .It plays a vital role in cell division, cell growth, wound healing ,and the breakdown of carbohydrates.Zn is also needed for the senses of smell and taste. 4 .8 mg for women and 11 mg for a adult man per day

11. 2.1.3 HOW DO METAL CARBONATES AND METAL BICARBONATES REACT WITH ACIDS?

12. Na 2 CO 3 (s)+2HCl( aq ) 2NaCl( aq )+CO 2 (g)+H 2 O(l) NaHCO 3 (s)+ HCl ( aq ) NaCl ( aq )+CO 2( g)+H 2 O(l) On passing CO 2 through lime water , it turns milky.This is due to the formation of CaCO 3. CO 2(g) +Ca(OH) 2 ( aq ) CaCO3 +H2O(l) (colorless) (white ppt ) On passing excess CO2,through CaCO3 solution ,calcium bi carbonate is formed. CaCO 3 +(s)+H 2 O(l)+CO 2 (g) Ca(HCO 3 ) 2( aq )

13. Metal carbonate /Metal bicarbonate + Acid very vigorous reaction Salt+carbon dioxide +water

14. 2.1.4 HOW DO ACIDS AND BASES REACT WITH EACH OTHER ACTIVITY 2.6(NEUTRALISATION) ACID+BASE SALT+WATER The effect of a base is nullified by an acid and vice- versa.This is known as neutralisation .

15. 2.1.5 REACTION OF METALLIC OXIDES WITH ACIDS ACTIVITY 2.7 METAL OXIDE +ACID SALT+WATER ( basic in nature) CuO+2HCl( dil ) CuCl 2( aq )+ H2O (BLACK) ( colourless ) BLUE-GREEN) ( colourless )

16. 2.1.6 REACTION OF A NON-METALLIC OXIDE WITH BASE 1.Ca(OH) 2 +CO 2 CaCO 3+ H 2 O (acidic ) ( white ppt ) salt 2. SiO 2+ 2NaOH Na 2 SiO 3 +H 2 O (silica) ( sodium silicate) ( acidic) ( salt) CONCLUSION Non metallic oxides are acidic in nature

17. 2.2 WHAT DO ALL ACIDS AND ALL BASES HAVE IN COMMON? ACTIVITY 2.8 MATERIALS REQUIRED: Aqueous solutions ofC 6 H 12 O 6 ,C 2 H 5 OH and HCl Two nails Two holed rubber cork .Three 100ml beaker 6 volt battery Filament lamp Switch

18. OBSERVATIONS: 1.The bulb starts glowing in case of acids due to the formation of ions. HCl ( aq ) IONISATION H +( aq ) + Cl - ( aq ) 2.Glowing of the bulb indicates –flow of current through the solution. 3.The bulb does not glow in case of Glucose and alcohol solution due to lack of ions or charge carriers. 4.Glucose and alcohol do not produce ions in water.

19. CONCLUSION 1.The cation present in acids is H + 2.Acids produce Hydrogen ions 3. H+( aq ) in solution are responsible for acidic nature 4.The anion present in bases is OH - 5 . Bases produce hydroxyl ions 6.Hydroxyl ions in solution are responsible for basic nature. - NaOH ( aq ) Na + + OH -

20. 2.2.1 WHAT HAPPENS TO AN ACID OR A BASE IN A WATER SOLUTION ACTIVITY 2.9 MATERIALS REQUIRED: SOLID NaCl Conc. H 2 SO 4 Dry Litmus paper Wet Litmus paper Guard tube containing anhydrous CaCl 2

21. PREPARATION OF HCl GAS FIG .2.4

22. CONCLUSION 1.Hydrogen ions in HCl are produced in the presence of water only 2.Hydrogen ions cannot exist alone 3.Acids give Hydronium or Hydrogen ion in water HCl+H 2 O H 3 O + + Cl – H + + H 2 O H 3 O+

23. What happens when a base is dissolved in water? NaOH Na+ ( aq ) +OH - ( aq ) Mg(OH) 2 H 2 O Mg ++ +2 OH - ( aq ) Bases generate (OH - ) in water H 2 O

24. ALKALIES –bitter in taste BASES BASES WHICH ARE SOLUBLE IN WATER e.g. KOH , NaOH,Ca (OH) 2 ,Mg(OH) 2 milk of magnesia WATER

25. NEUTRALISATION REACTION HX +MOH MX +HOH He effect of base is nullified by by an acid and vice-versa. HNO 3 + NaOH NaNO 3 +H 2 O ACID BASE SALT WATER

26. The acid must always be added slowly to water with constant stirring.GIVE SCINTIFIC REASON

27. SCIENTIFIC REASON If w ater is added to a concentrated acid ,the heat produced may cause the mixture to splash out and cause burns ,the glass container may also break due to excessive local heating. So care must be taken while mixing concentrated acid with water.

28. DILUTION

29. DILUTION The process in which the concentration of H+ or OH - decreases per unit volume

30. 2.3 HOW STRONG ARE ACID OR BASE SOLUTIONS? KEY WORDS 1.UNIVERSAL INDICATOR 2.PH SCALE OR SORENSON SCALE 3.CONC. OF H + IONS

31. PH SCALE

32. PH SCALE

33. ACTIVITY 2.11 PH OF SOME COMMON SUBSTANCES

34. STRENGTH OF ACIDS AND BASES DEPENDS ON ACIDS BASES 1.Number of H+ ions produced during its interaction with water 1.Number of OH- ions produced during its interaction with water 2.Acids that give rise to more H+ ions in aqueous solution are called strong acids 2.Bases that give rise to more OH- ions in aqueous solution are called strong bases 3.Acids that give rise to less number of H+ ions in aqueous solution are called weak acids 3.Bases that give rise to less number of OH- ions in aqueous solution are called weak bases. Strong Acids: HCL,HNO 3 ,H 2 SO 4,HBr, HI,HClO4 (per chloric acid) … Strong bases: NaOH , KOH, LiOH , RbOH , CsOH , Ca(OH) 2 ….. Weak acids: CH 3 COOH.HCOOH, H 2 CO 3, H 2 C 2 O 4( oxalic acid) ….. Weak bases NH 4 OH,Zn(OH) 2 ,Fe(OH) 3, Cu(OH) 2 ….

35. 2.3.1 IMPORTANCE OF PH IN EVERYDAY LIFE ARE PLANTS AND ANIMALS PH SENSITIVE ? 1)YES, Human body unctions within the PH range of 7.0-7.8 2) If the PH of blood<7.35 it leads to ACIDOSIS & If the pH >7.8 it leads to ALKOLOSIS 3)AQUATIC life becomes very difficult If PH <5.6

36. ACID RAIN RAIN (H2O) RAIN + SO 2 CO 2 NO 2 H 2 SO 3 H 2 CO 3 HNO 3 Cloud

37. DEMERITS OF ACID RAIN 1.It destroys the AQUATIC LIFE 2.It can damage historical monuments like TAJMAHAL 3.It can affect the trees which are at high altitudes 4.It affects soil bacteria

38. VENUS Venus One of the terrestrial planets life does not exist because It is made up of thick white and yellow clouds of H 2 SO 4

39. PH OF THE SOIL SOIL 1 . UPPER LAYER OF THE EARTH in which plants grow 2.COMPONENTS of soil organic matter soil bacteria Mineral particles Air water

40. PH OF THE SOIL IN YOUR BACKYARD ACTIVITY 2.12 2 gm SOIL +5ml WATER shake properly FILTER FILTRATE PH OF THIS FILTRATE HAS TO BE CHECKED BY USING UNIVERSAL INDICATOR OR PH METER. CONCLUSION: PH OF SOIL VARIES FROM 4.5 -7.5 Acidic effect can be neutralised by LIMING the soil By adding Ca(OH ) 2 or CaO or CaCO 3 (powered chalk) Alkaline effect canbe neutralised by adding manure

41. POINTS IN A NUT SHELL PLANTS PH RANGE 1.POTATOES 4.5 -6.0 2.CARROT 5.5-6.5 3.CAULI FLOWER,GARLIC, TOMOTO 5.5-7.5 4.ONION,CABBAGE 6.0 -7.5

42. PH IN OUR DIGESTIVE SYSTEM FOOD (OMPLEX MOLECULE )(STARCH )(C 6 H 10 O 5 )n DIGESTION HCl (acid) ENZYMES n C 6 H 12 O 6 ACIDITY During indigestion the stomach produces too much HCl &this causes pain &irritation.(PH decreases) REMEDY: By administering Mg(OH) 2(acts as an ANTACID) (It neutralises the excess acid)

43. PH CHANGE AS THE CAUSE OF TOOTH DECAY TOOTH DECAY DUE TO DECREASE IN PH OF THE MOUTH STARTS IF PH OF THE MOUTH IS <5.5 CHEMISTRY OF TOOTH DECAY: Tooth enamel is made up of Ca 3 (PO 4 ) 2(hardest substance in the body)-insoluble in the water .It is corroded when the PH in the mouth is <5.5. FOOD PARTICLES Bacteria in the mouth ACID (PYRUVIC A CID ) AND SUGAR(IN THE MOUTH glycolysis (CH3 (CO)COOH) PREVENTION : TO CLEAN THE MOUTH USING TOOTH PASTES WHICH ARE BASIC ,CAN NEUTRALISE THE EXCESS ACID AND PREVENT TOOTH DECAY

44. SELF DEFENCE BY ANIMALS AND PLANTS THROUGH CHEMICAL WARFARE 1.HONEY BEE STING LEAVES AN ACID HCOOH PH <7 CAUSES PAIN AND IRRITATION 2.STINGING HAIR OF NETTLE LEAVES INJECT HCOOH PH<7 CAUSES BURNING PAIN

45. 2.4 MORE ABOUT SALTS(HX) PREPARATION ,PROPERTIES &USES HX+MOH NEUTRALISATION MX+HOH 2.4.1 FAMILY OF SALTS Salts having the same + ve or – ve radicles are called the family of salts.The salts in the table belong to the family of sulphate salts Th SL.NO NAME OF THE SALT FORMULA ACID BASE 1 POTASSIUM SULPHATE K 2 SO 4 H 2 SO 4 KOH 2 SODIUM SULPHATE Na 2 SO 4 H 2 SO 4 NaOH 3 CALCIUM SULPHATE CaSO 4 H 2 SO4 Ca(OH)2 4 MAGNESIUM SULPHATE MgSO 4 H 2 SO 4 Mg(OH) 2

46. FAMILY OF SODIUM SALTS SL.NO NAME OF THE SALT FORMULA ACID BASE 1 SODIUM CHLORIDE NaCl HCl NaOH 2 SODIUM NITRATE NaNO 3 HNO 3 NaOH 3 SODIUM CARBONATE Na 2 CO 3 H 2 CO 3 NaOH 4 SODIUM SULPHATE Na 2 SO 4 H2SO4 NaOH

47. 2.4.2 P H OF SALTS ACTIVITY 2.1.4 SALT pH ACID USED BASE USED NaCl 7.0 HCl (STRONG) NaOH (STRONG KNO 3 7.0 HNO 3(STRONG) KOH( STRONG ) Al Cl 3 <7.0 HCl (STRONG) Al(OH) 3(WEAK) ZnSO 4 <7.0 H 2 SO 4 Zn(OH) 2 CuSO 4 <7.0 H 2 SO 4 Cu(OH )2 CH 3 COONa >7.0 CH3COOH NaOH Na 2 CO3 >7.0 H2CO3 NaOH

48. CONCLUSION SALTS OF STRONG ACID AND STRONG BASE ARE NEUTRA L PH =7.0 SALTS OF STRONG ACID AND WEAK BASE ARE ACIDIC PH <7.0 SALTS OF STRONG BASE AND WEAK ACID ARE BASIC PH>7.0

49. 2.4.3 CHEMICALS FROM COMMON SALT CaSO 4 MgCl 2 CaCl 2 MgSO 4 Ca(HCO 3 ) 2 NaCl Mg(HCO 3 ) 2 SEA WATER pH=8.3

50. ROCK SALT RECALL :DHANDI MARCH( M.K.GANDHI) Found in sea water,in salt wells,in inland lakes FOUND in H.P (MANDI) Saturated solution is pumped out and evaporated to get the salt ROCK SALT

51. PROPETIES OF THE ROCK SALT WHITE CUBIC CRYSTAL COLOURLESS CRYSTALLINE SOLID M.P. 820 ORDINARY SALT is hygroscopic ODOURLESS because of the presence of MgCl 2/ CaCl2 On heating it gives crackling noise ROCK SALT OR HALITE

52. S UPPORT THE STATEMENT .COMMON SALT –A RAW MATERIAL FOR CHEMICALS USED TO MAKE NaOH,NaHCO3,Na 2 CO 3 USED IN THE PREPARATION OF SOAP USED TO MAKE CaOCl 2, USED IN THE PACKING OF MEAT AND FISH USED FOR LEATHER TANNING USES OF HALITE

53. CHLOR-ALKALI PROCESS REACTANTS : 1.Aqueous solution of NaCl (Brine) 2.Water(H2O)

54. DEFINITION OF CHLOR-ALKALI PROCESS On passing current electricity through an aqueous solution of brine ,it decomposes to form Cl 2 ,NaOH and H 2.This is known as chlor -alkali process.Chlor for chlorine and alkali for sodium hydroxide. REACTIONS: 2NaCl +H 2 O CURRENT ELECTRICITY 2 NaOH +Cl 2 +H 2 ( aq ) (l) ( aq ) (g) (g)

55. REACTIONS AT ANODE AND CATHODE REACTION AT CATHODE : NaCl ( aq ) Na + ( aq ) + Cl - H 2 O H + ( aq )+ OH - H + +e (H) H +H H 2(AT CATHODE) Na + + OH - Na o H ( FORMED NEAR CATHODE)

56. REACTION AT ANODE Cl - + e ( Cl ) Cl + Cl Cl 2(g) YELLOW-GREEN ONE OF THE HALOGENS

57. USES OF THE PRODUCTS OF CHLOR-ALKALI PROCESS

58. USES OF HYDROGEN Extreamly good fuel because 150 kJ/g Used as a fuel in space ships in liquid form Used in oxy-hydrogen flame To cut steel because it produces Very high temperature Used to make MARGARINE Used to manufacture NH 3 which is used in the manufacture of urea and explosives.USED TO MANUFACTURE HCl ACID USED TO CLEAN STEEL HYDROGEN

59. MARGARINE MADE BY VEGETABLE OILS SEMI SOLID EMULSION-FIRST MADE IN 1869 IN FRANCE BUTTER SUBSTITUTE OBTAINED BY THE HYDROGENATION OF OILS C 17 H 34 O 2

60. USES OF CHLORINE USED TO CLARIFY DRINKING WATER USED IN SWIMMING USED IN PAPER POOLS AS DISINFECTANT INDUSTRY FOR BLEACHING WOODPULP USED FOR THE EXTRACTION OF GOLD AND PLATINUM USED IN THE MANUFACTURE OF CHCl 3 AND DDT USED TO MANUFACTURE TOXIC GASES NAMELY PHOGENE AND TEAR GAS COCl2 AND CCl3 NO2 USES OF CHLORINE

61. NaOH USED TO REMOVE ACIDIC IMPURITIES WHILE REFINING PETROLEUM USED TO MANUFACTURE SOAPS AND DETERGENTS FOR MERCERIZING COTTON USED TO MAKE PAPER AND ARTIFICIAL FIBRES USED IN DE-GREASING METALS BECAUSE GREASE IS ACIDIC USES OF NaOH

62. BLEACHING POWDER OR CHLORIDE OF LIME OR CALCIUM OXY CHLORIDE PREPARATION OF BLEACHING POWDER: Cl 2 (g) Ca(OH) 2 CaOCl 2 +H2O (DRY) YELLOWISH WHITE POWDER SOLUBLE IN WATER AND GIVES A STRONG SMELL OF CHLORINE

63. B LEACHING POWDER IS A POWERFUL GERMICIDE.SUPPORT THE STSTEMENT (2MARKS) 1 Kg BLEACHING POWDER CaOCl 2 + H 2 O Ca(OH) 2 +Cl 2 Cl 2 +H 2 O HCl+HOCl ( HYPOCHLOROUS ACID) GERMS + HOCl GERMS ARE KILLED 1000 KILO LITRES OF WATER

64. USES OF BLEACHING POWDER 1.CHIEFLY FOR BLEACHING COTTON,LINEN 2.USED FOR BLEACHING WOOD PULP IN PAPER FACTORY 3.USED TO MANUFACTURE CHCl 3 4.FOR THE STERILATION OF DRINKING WATER 5.USED AS AN OXIDISING AGENT IN CHEMICAL INDUSTRIES

65. BAKINGSODA OR SODIUM BI CARBONATE NaHCO 3 MILD NON -CORROSIVE BASE IT ACCELERATES COOKING NaCl +H2O+CO2+NH3 COLD CONDITION NH 4 Cl +NaHCO 3 EFFECT OF HEATING NaHCO3 373 K HEATING Na 2 CO 3 +H 2 O+CO 2

66. USES OF BAKING SODA 1.Used for making BAKING POWDER 2.U SED in making effervescent drinks (LIKE PEPSI,COCA –COLA etc. 3.Used in soda-acid fire extinguishers 4.Used in antacid as ingradient (because it is alkaline)

67. BAKING POWDER OR SODIUM SALT OF TARTARIC ACID TARTARIC ACID CH(OH)COOH CH(OH)COOH CH(OH) COONa CH(OH) COONa +CO2 +H2O ( BAKING POWDER) CO 2 PRODUCED DURING THE REACTION CAUSES BREAD OR CAKE TO RISE MAKING THEM SOFT AND SPONGY NaHCO3

68. WASHING SODA: Na2CO3.10 H2O PREPARATION(SOLVAY PROCESS)(1860) NH 3 +H 2 O+CO 2 NH 4 HCO3 NaCl+NH 4 HCO 3 NaHCO 3 +NH 4 Cl (WHITE PPT ) NaHCO 3 HEATING Na 2 CO 3 + H 2 O+CO 2 (SODA ASH) Na 2 CO 3 +10 H2O CRYSTALLISATION Na2CO3.10 H2O

69. USES OF WASHING SODA 1. USED IN LAUNDRY AS CLEANSING AGENT 2.USED FOR SOFTENING HARD WATER 3.USED TO MAKE NaOH , GLASS, SOAP, WATER GLASS, AND BORAX( INSECTICIDE)(Na 2 B 4 7 .10 H 2 O ) EFFLORESCENCE Na2CO3 .10H2O EXPOSED TO AIR Na2CO3.H2O+9H2O TRANSPAREN T LOSS OF H2O WHITE POWDER CRYSTALS

70. 2.4.4ARE THE CRYSTALS OF SALTS REALLY DRY? NO ,APPEARS TO BE DRY.(FIG.2.9) ACTIVITY 2.15

71. 2.4.4 ARE CRYSTALS OF SALTS REALLY DRY ? ACTIVITY 2.4.4

72. ARE THE CRYSTALS OF SALTS REALLY DRY? T he crystals of salts are seem to be dry, because they contain water of crystallization. This can be confirmed by heating the crystals in a boiling tube. During the process colour and shape will be changed. WATER OF CRYSTALLISATION: The fixed number of water molecules in one formula unit of a salt. They impart shape and colour to the salt.

73. PROMINENT SALTS

74. PLASTER OF PARIS(POP) ALBASTER PREPARATION : CaSO4.2H2O 373K CaSO 4 .1/2 H2O+1 1/2H2O ( GY PSUM) (POP) (HEMIHYDRATED CALCIUM SULPHATE) CaSO 4. 1/2 H 2 O 473K CaSO 4 + 1/2 H 2 O (POP) ( DEAD BURNT ) SETTING AND HARDENING OF POP POP sets to a hard mass which expands with hardening. The final product of setting is CaSO4.2H2O CaSO4.1/2H2O +3/4 H2O CaSO 4 .2H2O

75. USES OF POP 1.Used in surgery for plastering fractured parts of the body. 2.Used for preparing black board chalks 3. Used as a binder in the building industry 4.Used for making TOYS 5. Used for DECORATION 6.Used to prepare models of ARTIFICIAL DENTURES

76. HOME ASSIGNMENT 1.QUESTION- PP 18 2.QUESTIONS –PP 22 3.QUESTIONS –PP 25 4.QUESTIONS –Pp 28 5.QUESTIONS- Pp 33 6.EXERCISES-Pp34 &35 BEGIN WITH END IN MIND