Chemical tests - EMPA Practice

HideShow resource information
  • Created by: xxSonia
  • Created on: 06-05-15 13:42

Halide Ions

Chlorde, Cl-

Test

Add dilute nitric acid

Then add silver nitrate solution

Observation

White precipitate from colourlss solution

Equation

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

1 of 12

Halide Ions - bromide

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

2 of 12

Halide Ions - iodide, I-

Idiodide, I-

Test

Adddilute nitric acid

Silver nitrate solution

Observations

Very pale yellow precipitate from colourless solution

Equation

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

3 of 12

Hydrochloric acid

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)

4 of 12

Ammonia, NH3

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

5 of 12

Sulphur Dioxide gas , SO2

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

6 of 12

Carbonate Ion, CO3^2-

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

7 of 12

Hydrogen Carbonate, HCO3-

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)

8 of 12

Sulphate ion, SO4

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

9 of 12

Sulphide ions, S2-

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

10 of 12

Sulphide ions, S2-

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

11 of 12

hydroxide Ions, OH-

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)

12 of 12

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Acids, bases and salts resources »