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