Experiment QA1 Qualitative Analysis
Name:
Seat No.:
Date:
Grade:
1. Describe the sample.2. Report on the solubility of the sample in water.
3. Estimate, using universal test paper, the pH of an aqueous solution of the sample.
4. Heat a small amount of the solid sample in an ignition tube, at first gently and then strongly.
Report the observations.
5. Carry out a flame test and report the observations.
6. Report on the action of 2 M H2SO4 on an aqueous solution of the sample.
7. Report on the action of conc. H2SO4 on thesolidsample.
8. Report on the action of conc. HNO3 on the solid sample.
9. Report on the action of 2 M NaOH on an aqueous solution of the sample.
10.Report on the action of dilute aqueous NH3 on an aqueous solution of the sample.
11.Report on the action of a few drops of 0.2 M KMnO4 in 2 M H2SO4 on an aqueous solution of the sample.
12.Report on the action of zinc and 2 M H2SO4 on an aqueous solution of the sample.
From the result of the above tests, deduce which cation(s) and anion(s) may be present in the solid sample.
P.1
Experiment QA1 Qualitative Analysis
1. Describe the sample.
Solid, liquid, gas.
e.g. i. Green solid.
ii. Brown solution.
iii. White crystalline solid.
iv.Colourless liquid.
v.Blue liquid.
vi.Yellow viscous liquid.
Colour / InferenceRed / HgO, Ag2CrO4, Cu2O
Orange / Cr2O72-
Yellow / AgI, AgBr, Fe3+(dil.)
Green / CuCO3, Fe2+, Cr3+
Blue / Cu2+
Purple / MnO4-
Brown / Fe3+(conc.)
Black / CuO, MnO2, CuS, PbS
Pink / Co2+
White / Most compounds.
Probably does not contain atransition metal
2. Report on the solubility of the sample in water.
e.g. i. Very soluble.
ii. Soluble.
iii. Slightly soluble.
iv. Insoluble.
1. All salts of group I cations and NH4+ are soluble.
2. All nitrates are soluble.
3. All ethanoates are soluble.
4. All sulphates are soluble except those of Ba2+, Ca2+,Sr2+ and Pb2+.
5. All chlorides/bromides/iodides are soluble except those of Ag+, Cu+, Pb2+ and Hg22+.
6. All carbonates/phosphates/sulphites are insolubleexcept those of group I cations and NH4+.
7. All hydroxides are insoluble except those of group I cations, NH4+, Sr2+ and Ba2+.
8. All sulphides are insoluble except those of group Iand group II cations and NH4+.
P.2
Experiment QA1 Qualitative Analysis
3. Estimate, using universal test paper, the pH of an aqueoussolution of the sample
e.g. i. pH = 2
ii. pH = 7
iii. pH = 13
iv. pH = 9.5
4. Heat a small amount of the sample in an ignition tube, at first gently and then strongly.
Report the observations.
e.g. i.Gas evolved.
ii.Pungent gas evolved.
iii.Brown gas evolved.
iv.Sublimation.
v.Decrepitation. (spitting and cracking)
vi.Charring. (carbon produced)
vii.Colourless liquid condenses on cooler parts of tube.
Observation / InferenceSublimation. / NH4+ salts.
Decrepitation,
spitting and cracking. / Anhydrous salts that decomposewith evolution of gas.
e.g. Pb(NO3)2, KMnO4.
Charring.
(carbon produced) / CH3COO-, C2O42-.
Gas evolved which relights a glowing splint. / O2 produced by decomposition of oxide or nitrate.
Gas evolved which turns lime water milky. / CO2 produced by decomposition ofcarbonate or hydrogencarbonate.
Gas evolved which burns with a blue flame. / CO from decomposition of oxalate.
Brown gas evolved. / NO2 from a nitrate or Br2 froma bromide.
Colourless liquid condenses on cooler parts of tube. / Probably water from the decomposition of a hydrate,
a hydroxide or a hydrogencarbonate.
Pungent gas evolved which is alkaline. / NH3 from decomposition ofammonium salt.
P.3
Experiment QA1 Qualitative Analysis
5. Carry out a flame test and report the observation.
Flame colour / InferencePersistent yellow / Na+
Lilac / K+
Red/Orange / Ca2+, Sr2+, Li+
Pale green / Ba2+
Greenish blue / Cu2+
6.Report on the action of 2M HCl/2M H2SO4 on an aqueoussolution of the sample.
Observation / InferenceGas evolved which turns lime water milky. / CO2 from CO32- orfrom HCO3-
Gas evolved has a pungent smell, is acidic and turns dilute KMnO4 colourless. / SO2 from SO32-
Gas evolved smells with bad eggs and gives a black precipitate with lead nitrate solution. / H2S from S2-
Pungent acidic gas is evolved and a pale yellow precipitate forms. / SO2 or S from S2O32-
Dark brown acidic gas evolved. / NO2 from NO2-
Pale green gas evolved which bleaches indicator. / Cl2 from ClO-
Acidic gas evolved which smells of vinegar. / CH3COOH from CH3COO- or
HCOOH from HCOO-
P.4
Experiment QA1 Qualitative Analysis
7. Report on the action of conc. H2SO4 on the solid sample.
e.g. i. Colourless gas evolved.
ii.Brown fumes evolved.
Observation / InferencePale yellow vapour. / Possibly HNO3 vapour from NO3-
Steamy fumes evolved which give dense white smoke with NH3(g). / HCl from Cl-
Brown-orange fumes. / Br2 from Br-
Purple fumes. / I2 from I-
Gases evolved which burn with a blue flame and turn lime water milky. / CO and CO2 from C2O42-
Gas evolved which burns with a blue flame. / CO from HCOO-
8. Report on the action of conc. HNO3 on the solid sample.
e.g. i. Brown fumes evolved.
(most reducing agents such as C, S, SO32-)
ii. Black precipitate. (Inference: I-)
(I- + NO3- + 2H+ I2 + NO2 + H2O)
9. Report on the action of 2 M NaOH on an aqueous solution of thesample.
e.g. i.A blue gelatinous precipitate forms.
ii.A white gelatinous precipitate soluble in excessNaOH.
iiiNo precipitate at any stage.
Observation / InferenceWhite gelatinous precipitate. / Mg2+, Al3+, Zn2+
Dirty green gelatinous precipitate. / Fe2+
Reddish brown gelatinous precipitate. / Fe3+
Pale blue gelatinous precipitate. / Cu2+
Dark brown precipitate. / Ag+
White powder gelatinousprecipitate / Pb2+
No precipitate. / Na+, K+, NH4+
Note: Al(OH)3, Zn(OH)2 and Pb(OH)2 are soluble in excess 2M NaOH.
P.5
Experiment QA1 Qualitative Analysis
10. Report on the action of dilute aqueous NH3 on an aqueoussolution of the sample.
e.g. i. White precipitate formed.
ii. Initial pale blue precipitate which dissolvesto form deep blue solution.
Observation / Inference / Action of excess NH3on precipitateWhite gelatinous precipitate / Mg2+/Al3+ / Insoluble
White gelatinous precipitate / Zn2+ / ppt dissolves to form colourless solution
White powderly precipitate / Pb2+ / Insoluble
Dirty green precipitate / Fe2+ / Insoluble
Reddish brown precipitate / Fe3+ / Insoluble
Pale blue precipitate / Cu2+ / ppt dissolves to form deep blue solution
Dark brown precipitate / Ag+ / ppt dissolve to form colourless solution
11. Report on the action of a few drops of 0.2 M KMnO4 on an aqueous solution of the sample.
e.g.i No visible change.
ii.The acidified KMnO4 solution is turned frompurple to colourless. (This indicates thatthe sample is a reducing agent)
12. Report on the action of zinc and 2M H2SO4 on an aqueoussolution of the sample.
e.g. i.No visible change.
ii.The aqueous solution of the sample decolourized.
iii.Colour of solution changes from orange to green.
N.B.Any positive result shows that the sample is anoxidizing agent.
P.6
Experiment QA1 Qualitative Analysis
Gas / Colour / smell / Test / EquationsHydrogen / Colourless / Odourless / Burns with a ‘pop’ sound / 2H2+O2 2H2O
Oxygen / Colourless / Odourless / Relights glowing splint
Carbon dioxide / Colourless / Odourless / Turns lime water milky / CO2+Ca(OH)2 CaCO3 +H2O
Carbon monoxide / Colourless / Odourless / Burns with blue flame / 2CO+O2 2CO2
Ammonia / Colourless / Pungent smell /
- turns red litmus blue
- forms white fumes with HCl
Hydrogen chloride / Colourless / Irritating smell / forms white fumes with NH3 / NH3+HCl NH4Cl
Chlorine / Greenish yellow / Choking smell / Turns blue litmus red and then bleaches it / Cl2+H2O HCl+HOCl
Bromine / Reddish brown / Choking smell / Turns blue litmus red and then bleaches it / Br2+H2O HBr+HOBr
Iodine / violet / Choking smell / Turns starch blue
Sulphur dioxide / Colourless / Sulphur smell / Turns acidified potassium dichromate green / Cr2O72-+14H++6e- 2Cr3+
+7H2O
SO2+2H2O 4H++SO42-+2e-
Nitrogen dioxide / brown / Pungent smell / Turns blue litmus red
Nitrogen monoxide / Colourless / Odourless / Forms brown fumes in air / 2NO+O2 2NO2
Water vapour / Colourless / Odourless / Turns anhydrous copper(II) sulphate blue / CuSO4+5H2O CuSO45H2O
P.7