Chemistry chapter 11: Qualitative Analysis
test for cations
iron(II)
iron(III)
copper (II)
Lead(II)
calcium
zinc
ammonium
aluminium
when added with sodium hydroxide (NaOH), forms a white precipitate, it is soluble in excess and gives off a colourless solution, if added with aqueous ammonium (NH3), forms a white precipitate, insoluble in excess
ammonia (NH4) produced after added with NaOH and warmed
forms a white precipitate when added with NaOH, no precipitate is formed if added with aq NH3
forms a light blue precipitate when added with NaOH, insoluble in excess, when added with aq NH3, it forms a light blue precipitate, soluble in excess giving a dark blue solution
forms a green precipitate when added with NaOH, insoluble in excess, when added with aq NH3, forms a green precipitate, insoluble in excess
forms a reddish brown precipitate when added with NaOH, insoluble in excess, when added with aq NH3, forms a reddish brown ppt, insoluble in excess
when added with NaOH, forms a white ppt, soluble in excess and gives a colourless solution, when added with aq NH3, forms a white ppt, insoluble in excess
when added with NaOH, forms a white ppt, soluble in excess and gives a colourless solution, when added with aq NH3, forms a white ppt, soluble in excess, and gives a colourless solution
test for anions
chloride
iodide
carbonate
nitrate
to test, add dilute acid, if carbonate is present, effervescence is observed, carbon dioxide is produced
sulfate
to test, acidify with dilute nitric acid, then add aqueous silver nitrate, if chloride is present, it forms silver chloride, AgCl
to test, acidify with dilute nitric acid, then add aqueous silver nitrate, if present, it forms a pale yellow ppt, silver iodide, AgI
to test, add aqueous sodium hydroxide, then add aluminium foil and warm carefully, if present, ammonia is produced
to test, acidify with dilute nitric acid, then add aqueous barium nitrate, if present, it forms a white ppt, barium sulfate BaSO4
test for gases
chlorine
hydrogen
carbon dioxide
oxygen
ammonia
sulfate dioxide
to test, dip a damp red litmus paper into the solution to be tested, if present, the red litmus paper turns blue
if present, it forms a white ppt when bubbled into limewater
add red/blue litmus paper to solution to be tested, if chlorine is present, litmus paper will be bleached, their colour will be lost, no colour
to test, bring a lighted splint to the mouth of the test tube with the solution, if hydrogen present, the lighted splint is extinguished with a "pop" sound
bring a glowing splint to the mouth of the test tube with the solution, if oxygen is present, the splint will be lighted again
to test, add aqueous potassium manganate(VII) to the solution, if sulfur dioxide is present, potassium manganate(VII) will turn colourless
6 types of reactions
combustion, example: C +O2 -> CO2
metal and non metal, example: 2 Na + Cl2 -> 2NaCl
decomposition, example: CuCO3 -> CuO + CO2;2H2O -> 2H2O + O2
acid base reaction, an example would be H2SO4 + 2NaOH -> Na2SO4 + 2H2O
displacement, example: Cl2 + 2KI -> I2 + 2KCl
precipitation, an example would be 2 NaOH + ZnCl2 -> Zn(OH)2 + 2NaCl
solubility rules
all carbonates are INSOLUBLE in water, except sodium, potassium and ammonium
all oxides and hydroxides are INSOLUBLE in water except group1 elements, Ca(OH)2 is sparingly soluble
most sulfates are soluble in water, except lead(II), calcium, barium (PbBaCa)
all sodium, potassium, ammonium compounds are soluble in water
most chlorides, bariums, iodides are soluble in water except lead(II), silver (PbAg)
all nitrates are soluble in water