ion tests

Question 1

test, observation and eq for iodide

Answer 1

test: dilute nitric acid then silver nitrate then ammonia

ob: yellow precipitate and insoluble in conc ammonia. ppt turns white

Ag+ + I- (aq) -> AgI (s)

Question 2

test, observation and eq for bromide

Answer 2

test: dilute nitric acid then silver nitrate then ammonia

ob: cream precipritate dissolves in conc ammonia

Ag+ (aq) + Br- (aq) -> AgBr (s)

AgBr (s) + NH3 (aq) -. AgNH3 + Br-

Question 3

test, observation and eq for chloride

Answer 3

test: dilute nitric acid then silver nitrate then ammonia

ob: white precipriate dissolves in dilute ammonia (NH3)

Ag+ + Cl- -> AgCl
AgCl + 2NH3 -> Ag(NH3)2 + Cl-

Question 4

test, observation and eq for hydroxide

Answer 4

test: ammonium salt (NH4) and test gas with moist red litmus paper

ob: gas evolved turned litmus paper blue

OR

test: add Mg2+ to get white ppt (Mg(OH)2

NH4+ + OH- -> NH3 + H2O

Mg2+ + 2OH- -> Mg(OH)2

Question 5

test, observation and eq for sulfate

(also reverse test for Ba2+)

Answer 5

test: BaCl2

ob: white ppt

Ba2+ + SO4 2- -> BaSO4

Question 6

test, observation and eq for carbonate and hydrogen carbonate

Answer 6

test: dilute acid (nitric acid)

observation: effervescence

CO3 2- + 2H+ -> CO2 + H2O

HCO3- + H+ -> CO2 + H2O