inorganic chemistry

• Test for SO42-


  • acidify with dilute HCl
  • add BaCl
  • white precipitate of BaSO4
• SO42-


  1. Acidify with dilute HCl

  2. Add BaCl

  White precipitate of BaSO4
• CO32-


  Add dilute HCl

  Effervescence

  Gas produced turns limewater cloudy
• OH-


  Damp red litmus paper

  Turns from red to blue
• Halide ion


  • Cl-

  Br-

  I-
• Cl-


  1. Acidify with dilute HNO3

  2. Add AgNO3

  3. (Add dilute NH3 followed by conc. NH3)

  White precipitate dissolves in dilute NH3
• Br-


  Cream precipitate

  Dissolves in conc. NH3 (NOT with dilute)
• 1. 
     

  Yellow precipitate

  Insoluble in conc. NH3
• Mg2+


  In separate test-tubes:

  • Add dilute NaOH
  • Add dilute H2SO4

  With OH-: white precipitate

  With SO42-: nvc
• Ca2+


  Flame test: Brick-red

  In separate test-tubes:

  • Add dilute NaOH
  • Add dilute H2SO4

  With OH-: white precipitate/suspension

  With SO42-: slight white precipitate
• Sr2+


  Flame Test: red

  In separate test-tubes:

  • Add dilute NaOH
  • Add dilute H2SO4

  With OH-: nvc

  With SO42-: white precipitate
• Ba2+


  Flame Test: green

  In separate test-tubes:

  • Add dilute NaOH
  • Add dilute H2SO4

  With OH-: nvc

  With SO42-: white precipitate
• NH4+


  1. Add NaOH

  2. Heat sample

  3. Hold damp red litmus paper at test tube mouth

  litmus paper will turn from red to blue.
• Co2+


  aqua ion [Co(H2O)6]2+

  Add NH3 dropwise to excess (OR add Cl- ions)

  Pink solution → blue-green precipitate → straw-yellow solution (pink → blue solution)
• Cu2+


  Aqua ion [Cu(H2O)6]2+ (pale blue solution)

  Add dilute NaOH: Pale blue precipitate

  Add excess NaOH: nvc

  Add dilute NH3: Pale blue precipitate

  Add conc. NH3: Dark blue solution

  Add Na2CO3: Green-blue precipitate

  Add NaCl: Yellow solution
• Fe2+


  Aqua ion [Fe(H2O)6]2+ (green solution)

  Add dilute NaOH: Green precipitate

  Add excess NaOH: nvc

  Add dilute NH3: Green precipitate

  Add conc. NH3: nvc

  Add Na2CO3: Green precipitate
• Fe3+


  Aqua ion [Fe(H2O)6]3+ (violet/brown/yellow sol.)

  Add dilute NaOH: Orange-brown precipitate

  Add excess NaOH: nvc

  Add dilute NH3: Orange-brown precipitate

  Add conc. NH3: nvc

  Add Na2CO3: Orange-brown precipitate and effervescence

  Add NaCl: Yellow solution
• Al3+


  Aqua ion [Al(H2O)6]3+ (colourless sol.)

  Add dilute NaOH: White precipitate

  Add excess NaOH: Precipitate dissolves → colourless sol.

  Add dilute NH3: White precipitate

  Add conc. NH3: nvc

  Add Na2CO3: White precipitate and effervescence
• Alkene -C=C-


  Shake with bromine water

  Solution changes colour from orange to colourless
• Halogenoalkane R-X


  1. Add NaOH(aq) and warm

  2. Acidify with HNO3

  3. Add AgNO3 (aq)

  Precipitate of AgX:

  • AgCl = white
  • AgBr = Cream
  • AgI = yellow
• Alcohol R-OH


  1o and 2o: Add acidified potassium dichromate (VI) K2Cr2O7

  Solution turns from orange to green

  3o: Solution remains orange

  All: Add metallic Na

  Effervescence (H2)
• Aldehyde R-CHO


  Warm with Fehling's solution (contains Cu2+ ions)

  Orange-red precipitate forms, so solution turns from blue → red

  Warm with Tollens' reagent (AgNO3 + NaOH + dilute NH3)

  Silver precipitate (mirror) forms
• Carboxylic Acid R-COOH


  Add a carbonate (e.g. Na2CO3 (s) or NaHCO3(aq))

  CO2 released - will turn limewater cloudy
• Barium sulfate is insoluble, so it can be used as an X-ray contrast agent.
• Sulfur dioxide (SO2) is produced by the combustion of fossil fuels containing sulfur impurities or during smelting processes involving sulfide ores.
• The reaction between hydrochloric acid and calcium oxide produces calcium chloride and water.
• Calcium chloride has many uses such as deicing roads during winter, preserving food, and making plastics.
• Periodic Table


  Arranges the known elements according to proton number

  
• Period


  • All the elements along a period have the same number of electron shells
• Group


  • All the elements down a group have the same number of outer electrons, this number is indicated by the group number
• Blocks in the Periodic Table

  • s-block (groups 1 and 2)
  • p-block (groups 3 to 0)
  • d-block (transition metals)
  • f-block (radioactive elements)
• Electron configurations of the blocks are often linked to other trends within the Periodic Table

  
• Periodicity


  The study of trends in the Periodic Table

  
• Along a period


  Atomic radius decreases
• Reason for atomic radius decreasing along a period


  Increased nuclear charge for the same number of electron shells, pulling the outer electrons closer to the nucleus
• Down a group


  Atomic radius increases
• Group II metals


  Lose two electrons to form 2+ ions when they react in order to achieve a full outer shell
• Reason for atomic radius increasing down a group


  Addition of an electron shell each time, increasing the distance between the outer electrons and the nucleus, and increased electron shielding reducing nuclear attraction
• Atomic radius of group II metals

  • Increases down the group due to additional electron shells
• Reactivity of group II metals

  Increases down the group due to increased electron shielding making the outer electrons easier to lose