Chapter 8 Salt part 6

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Chemistry Form 4: UPSI/SLISS 2012
Chapter 8: Salt (Part 6)

8.2 QUALITATIVE ANALYSIS

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Chapter 8 Salt part 6

  1. 1. NURUL ASHIKIN BT. ABD RAHMAN PART 6
  2. 2.  State the meaning of qualitative analysis. Make inferences on salts based on their colour and solubility in water. Describe tests for the identification of gases.
  3. 3. Qualitative analysis is a chemical method to The ions present determine the in salt are need tosubstances present in a identify in thiscompound but not their qualitative quantities. analysis
  4. 4. Observation physical properties ofsalts Action of heat on salt Make aqueous solution of the salt to test for anions and cations present Carry out confirmatory tests
  5. 5. 11 Click to add Title Colour and solubility of the salt22 Click to add Title Gas test13 Click to add Title salt Effect of heat on24 Click to add Title for anions Confirmatory test15 Click to add Title for cations Confirmatory test
  6. 6. SALT COLOUR SOLID AQUEOUS SOLUTIONCa2+ , Mg 2+ , Al3+ , Pb2+ , NH4+ white colourlessCuSO4, Cu(NO3)2 Blue BlueCuCl2 Green BlueFeSO4, Fe(NO3)2, FeCl2 Green GreenFe(SO4)3, Fe(NO3)3, FeCl3 Brown Yellow/BrownishCuCO3 Green (Insoluble)PbO Brown when Hot & Insoluble Yellow when cooledCuO black InsolubleZnO Yellow when Hot & Insoluble White when cooledPbCl2 white Insoluble in cold water but soluble in hot waterPbI2 Yellow Insoluble in cold water but soluble in hot water
  7. 7. Gas Colour Smell Confimatory TestO2 colourless Odourless Light up a glowing wooden splinterH2 colourless Odourless Produces a ‘pop’sound with lighted woodenCO2 colourless Odourless Turn lime water cloudyNH3 colourless Pungent smell Turn moist red litmus paper blueCl2 Grenish Pungent smell Bleaches moist red litmus paper Yellow Turn moist blue LP to red and bleaches it.HCl colourless Pungent smell Form dense white fumes with ammonia gasNO2 Brown Pungent smell Turn moist blue litmus paper to redSO2 colourless Pungent smell Turn moist blue litmus paper to red
  8. 8.  Describe the action of heat on salts. Describe the tests for anions. State observation of reaction of cations with sodium hydroxide solution and ammonia solution. Describe confirmatory tests for Fe2+ , Fe3+ ,Pb2+ and NH4+ Plan qualitative analysis to identify salts.
  9. 9. When Salt are HeatedA colour Release achange certain gas Release of water vapour
  10. 10. Heating CO3 salt • All carbonates are decomposed by heat to release CO2 except K2CO3 and NaCO3. • MCO3 MO + CO2 • CO2 will turn lime water,Ca(OH)2 milky (CaCO3 +H2O) Heating NO3 salt• Most metal nitrate decompose to produce a metal oxide, nitrogen oxide and oxygen.• KNO3 & NaNO3 produced Oxygen gas and nitrites when heated• NO2 (brown gas: acidic) , turn moist blue litmus paper red.• O2 relight glowing wooden splinter.
  11. 11. Heating SO4 salt• All suphate salt are not decomposed by heat.• Some (Fe, Zn, Cu) will decomposed during strong heating producing sulphur trioxide gas.• Ex: ZnSO4  ZnO + SO3 Heating Chloride salt• All chloride salts are not decomposed by heat except ammonium chloride.• NH4Cl produced white fumes.• Ex: NH4  NH3 + HCl
  12. 12. Gas produced Types of ion CO2 CO3 2- (except Na2CO3, K2CO3) O2 NO3- NO2 and O2 NO3- (excepts NaNO3, KNO3) SO2 SO4 2- NH3 NH4 +
  13. 13. Anion Confirmatory TestCO32- • Bubbles with dilute acid and the gas produced will cause limewater milkySO42- • Mixed with dilute sulphuric acid and barium chloride and a white precipitate is formed. Cl- • Mixed with dilute nitric acid followed by silver nitrate solution and a white precipitate is formedNO3- • Brown ring test and a brown ring will be formed.
  14. 14. Cation NaOH Solution NH3 Solution Ca2+ • White precipitate formed. • No reaction • Not soluble in excessMg2+ • White precipitate formed. • White precipitate formed. • Not soluble in excess • Not soluble in excess Al3+ • White precipitate formed. • White precipitate formed. • Soluble in excess • Not soluble in excess Zn2+ • White precipitate formed. • White precipitate formed. • Soluble in excess • Soluble in excess
  15. 15. Cation NaOH Solution NH3 Solution Pb2+ • White precipitate formed. • White precipitate formed. • Soluble in excess • Not soluble in excess Fe2+ • Green precipitate formed. • Green precipitate formed. • Not soluble in excess • Not soluble in excess Fe3+ • Brown precipitate formed. • Brown precipitate formed. • Not Soluble in excess • Not soluble in excess Cu2+ • Blue precipitate formed. • Blue precipitate formed. • Not soluble in excess • Not Soluble in excess and a dark blue solution is producedNH4+ • White precipitate formed. • No reaction • Soluble in excess
  16. 16. Confirmatory Tests for Fe 2+ , Fe3+ ,Pb2+, NH4+Cation Specific reagent Observation Pb2+ • KI, NaI • Yellow precipitate, soluble in hot water and recrystallises when cooled • KCl, NaCl,HCl • White precipitate, soluble in hot waterand recrystallises when cooled • K2SO4, Na2SO4, • White precipitate, insoluble in hot H2SO4 water
  17. 17. Confirmatory Tests for Fe 2+ , Fe3+ ,Pb2+, NH4+ Cation Specific reagent Observation Fe2+ • Potassium • Light blue precipitate hexacyanoferreta (II) K4Fe(CN)6 • Potassium • Dark blue precipitate hexacyanoferreta (III) K3Fe(CN)6 • Acidified KMnO4 • Purple colour decolourises
  18. 18. Confirmatory Tests for Fe 2+ , Fe3+ ,Pb2+, NH4+ Cation Specific reagent Observation Fe3+ • Potassium thiocyanate, • Brown precipitate KSCN formed. • Not soluble in excess • Potassium • Dark blue precipitate hexacyanoferrate (II) , K4Fe(CN)6 • Potassium • Greenish-brown hexacyanoferrate (II) , solution K4Fe(CN)6 NH4 + • Nessler reagent • Brown precipitate
  19. 19. PLAN QUALITATIVE ANALYSIS TO A IDENTIFY SALTSObservation on the physical properties of salt B Action of heat on salt C Test for cations and anions D Confirmatory test for cation and anions

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