quantitative analysis Flashcards
green coloured compounds
copper (II) carbonate
iron (II) salts
blue coloured compounds
copper (II) salts
brown coloured compounds
copper metal, iron (III) compounds
black coloured compounds
copper (II) oxide, iron (II) oxide, carbon, iodine crystals??
yellow coloured compounds
lead (II) oxide, lead (II) iodide, silver bromide, silver iodide
cations in cation tests
zinc, aluminium, calcium, copper (II), iron (II), iron (III), ammonium, sodium, potassium
solubility of zinc ions in reagents
white ppt (Zn(OH)2); soluble in excess
white ppt (Zn(OH)2); soluble in excess
solubility of aluminium ions in reagents
white ppt Al(OH)3; soluble in excess
white ppt Al(OH)3; insoluble in excess
solubility of calcium ions in reagents
white ppt Ca(OH)2; soluble in excess
no ppt formed
solubility of Cu2+ ions in reagents
blue ppt Cu(OH)2; insoluble in excess
blue ppt Cu(OH)2; soluble in excess
solubility of Fe2+ ions in reagents
green ppt Fe(OH)2; insoluble in excess
green ppt Fe(OH)2; insoluble in excess
solubility of Fe3+ ions in reagents
red brown ppt; insoluble in excess
red brown ppt; insoluble in excess
solubility of nh4+ ions in reagents
no ppt; ammonia given off upon heating
no ppt
why dont calcium ions form a precipitate in aqueous ammonia
aqueous ammonia has a low concentration of OH- ions so hard for products to form, and Ca(OH)2 is partially soluble in water, meaning any product formed is likely dissolved
why are most precipitates insoluble in excess
most metal hydroxides are basic and are insoluble in bases because they react with acids. exceptions are zinc and aluminium because they are amphoteric
anions to test for
carbonate, chloride, iodide, sulfate, nitrate
how to test for carbonate ion
add dilute acid and bubble gas involved into limewater. a white ppt will be formed in it
how to test for chloride ion
add dilute nitric acid then silver nitrate. a white ppt will be formed (AgCl)
how to test for iodide ion
add dilute nitric acid then aqueous silver nitrate. a yellow ppt will be formed (AgI)
how to test for sulfate ion
add dilute nitric acid then aqueous barium chloride. a white ppt will be formed (BaSO4)
how to test for nitrate ion
add aqueous sodium hydroxide and aluminium. warm mixture and test with damp red litmus paper. litmus paper will turn blue because ammonia gas is produced
processes behind nitrate ion test
nitrate ion is reduced to ammonium ion by aluminium, and then reacts with OH- ion in sodium hydroxide to produce ammonia gas
why are acids added before the testing for anions
ascertain that carbonate ions are not present
gases to test for
hydrogen, oxygen, carbon dioxide, chlorine, ammonia, sulfur dioxide??
how to test for hydrogen
burning splint at mouth of test tube is extinguished with a pop sound
how to test for oxygen gas
glowing splint in test tube is reignited
how to test for carbon dioxide gas
bubble into water, white ppt is formed
how to test for chlorine gas
place moist blue litmus paper at mouth of test tube, blue litmus paper turns red and is then bleached
gas is also yellow-green and pungent
how to test for ammonia gas
place moist red litmus paper at mouth of test tube, litmus paper turns blue
how to test for sulfur dioxide
place filter paper soaked with potassium manganate at mouth of test tube. potassium manganate turns colourless
why must litmus paper be moistened for gas testing
allows gases to dissolve onto litmus paper to form H+ or OH- ions that cause litmus papers to change colour
