5.3.2 qualitative analysis

Question 1

testing for carbonate

Answer 1

add any dilute acid and observe effervescence

bubble gas through limewater to test for CO2 - will turn limewater cloudy

2HCl + Na2CO3 > 2NaCl + H2O + CO2

fizzing due to CO2 would be observed if a carbonate was present

Question 2

testing for sulfate

Answer 2

acidified BaCl2 - reagent

if barium chloride is added and sulfate ions are present, white ppt forms

Ba2+ (aq) + SO42- (aq) > BaSO4 (s)

acid reacts with carbonate impurities that are found in salts which would form a white barium carbonate ppt, false result

Question 3

halide ions test

Answer 3

made acidic with nitric acid > reacts with carbonates to prevent Ag2CO3 formation, masking observations

silver nitrate, AgNO3

silver chloride + dilute ammonia > [Ag(NH3)2]+

silver bromide + conc ammonia > [Ag(NH3)2]+

silver iodide doesnt react - too insoluble

Question 4

test for ammonium

Answer 4

react warm NaOH to form NH3

identified by pungent smell or turning red litmus paper blue