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406 Qualitative Analysis Group 2, add a few drops of, sodium hydroxide…
406 Qualitative Analysis Group 2
ammonia
Zn 2+
white precipitate is formed
white precipitate insoluble
Al 3+
white precipitate is formed
white precipitate dissolves to form colourless solution
Ca 2+
no precipitate is formed
no precipitate is formed
Cu 2+
light blue ppt. formed
light blue precipitate dissolves to form dark blue solution
Fe 2+
green ppt. formed
green precipitate insoluble
Fe 3+
reddish-brown ppt. formed
red-brown precipitate insoluble
tests for anions
CO3 2-
test
add dilute acid and bubble gas into limewater
observation
effervescence observed, colourless, odourless gas (CO2) evolved forms a while precipitate with the limewater
SO4 2-
test
add dilute nitric acid and barium nitrate solution
observation
a white precipitation is formed
Cl-
observation
white precipitate formed
test
add dilute nitric acid then silver nitrate solution
I-
test
add dilute nitric acid then add silver nitrate solution
observations
yellow precipitate
NO3-
add sodium hydroxide solution then add a piece of aluminium foil and warm the solution
effervescence of a colourless and pungent gas which turns moist red litmus paper blue is observed
test for gases
ammonia
test
place moist red litmus at the mouth of the test tube
observations
colourless and pungent gas (NH3) evolved, turning moist red litmus blue
chlorine
test
place moist blue litmus at the mouth of the test tube
observations
pale greenish-yellow and pungent gas evolved (chlorine gas) turns moist blue litmus red and bleached
oxygen
test
insert a glowing splint at the mouth of the test tube
observation
colourless and odourless gas produced relights the glowing splint
hydrogen
test
place a lighted splint at the mouth of the test tube
observation
flame is extinguished with a "pop" sound
add a few drops of
Cu 2+
adding few drops
light blue ppt
adding excess
light blue precipitate is insoluble
Fe 2+
adding excess
green ppt insoluble
adding few drops
green ppt
Ca 2+
adding few drops
white ppt formed
adding excess
white ppt insoluble
Fe 3+
adding few drops
red-brown ppt formed
adding excess
red-brown ppt insoluble
Al 3+
adding few drops
white ppt formed
adding excess
white ppt dissolves to form a colourless solution
NH4 +
adding few drops
no ppt formed
when heated, colourless, pungent ammonia gas produced
turns moist litmus blue
adding excess
no change
Zn 2+
adding few drops
white ppt formed
adding excess
white ppt dissolves to form a colourless solution
sodium hydroxide cation test
add a few drop of sodium hydroxide solution
white ppt
soluble in excess
insoluble in excess
Ca 2+
Al 3+
Zn 2+ / Al 3+
light blue ppt
Cu 2+
green ppt
insoluble in excess
Fe 2+
Cu 2+
reddish-brown ppt
insoluble in excess
Fe 3+
no ppt