Chemical tests - EMPA Practice

Chlorde, Cl-

Test

Add dilute nitric acid

Then add silver nitrate solution

Observation

White precipitate from colourlss solution

Equation

Ag+ (aq) + Cl- ==> AgCl

Bromide,Br-

Test

Add dilute nitrc aci.

Then add silver nitrate solution

Observation

very pale cream precipitate from a colurless solution

Equation

Ag+ + Br- ==> AgBr

Idiodide, I-

Test

Adddilute nitric acid

Silver nitrate solution

Observations

Very pale yellow precipitate from colourless solution

Equation

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

Test1

Add HCl to blue litmus paper

litmus paper changes to colour red

Test 2

Add ammnia solution to HCl

white amnum chloride is produced.

Equation

NH3(g) + HCl ==> NH4Cl (s)

Test

Add 2cm^3 of alkaline to boiling tube.

Add 2cm^3 of ammonium solution

Heat the mixture

Remove tube once bubbles are seen and place red litmus paper over tube

Observations

Red litmus paper turns blue when in contact with gas

Test1

Sodiium Sulphate in a test tube

Add 3ml of HCl to t testtube

Warm gently

Hold moist litmus paper over test tube when gas is produced

Observations

Litmus paper:

Blue ==> Red

Red ==> no change

Test 2 ( still use results from test one )

Add 1 drop of Acidified pottassium mangnate onlitmus paper, hold paper in gas

Observations

Acidified potasium manganate turns colour from purple to colourless

Test

Add dilute strong acid to solid carbonate - if colourless gas is given off with lime water

observation

Fizzing colourless gas is produced

Turns lime water into milky, fine white precipitate

Equation

CO3^2-- (s) + 2H+ (aq) ==>H2O(l)+ CO2

Test

Heat stronglyand test if any CO2 is given off. Collect CO2 and see if lime water goes into a white precipitate

Observation

Once gas is collected, a white precipitate should form in lime water

Equation

HCO3- + H+ ( aq) ==> H2O(l) + CO2g)

test

Add HCl and few drops of barium chloride or nitrate solution

Observation

A white precipitate of barium sulphate

Equation

Ba2+ (aq) + SO4^2- ===> BaSO4

Test 1- If soluble add a few drops of lead(III) ethonate solutiion 

Observation 

Black Precipitate of lead sulphate

Equation

Pb2+ (aq) + S2- (aq) ==> PbS

Test 2

if solid add dilute HCl acid and test with damp ethonate paper 

Observations

'Rotten Eggs' smell of hydrogen sulphide . Gas turns lead(II) ethonate paper black

Equations

MS (s) + S2- (aq) ==> PbS(s)

MS = Pb or Fe or Cu or Ni e.t,c

Test 1- If soluble add a few drops of lead(III) ethonate solutiion 

Observation 

Black Precipitate of lead sulphate

Equation

Pb2+ (aq) + S2- (aq) ==> PbS

Test 2

if solid add dilute HCl acid and test with damp ethonate paper 

Observations

'Rotten Eggs' smell of hydrogen sulphide . Gas turns lead(II) ethonate paper black

Equations

MS (s) + S2- (aq) ==> PbS(s)

MS = Pb or Fe or Cu or Ni e.t,c

Test

Add Fe2+ solution into OH- solution

Observation

Iron hydroxide turns almost white if oxygen is execute but is a 'dirty green' precipitate and turn brown when exposure to the air.

Equation 

Fe2+ (aq) + 2OH- (aq) ==> Fe(OH)2(s)

test 2 

Add Fe3+ solution into Oh- solution

Observations

Iron(III) hydroxide is an orange brown precipitate 

Equations

Fe3+ (aq) = 3OH- (aq) ==> Fe(OH)3 (s)