Chemistry Practicals Cheat Sheet By Aman

Chemistry Salt Analysis Cheatsheet

Copyright © 2007 by Aman BAtra. No part of this document may be

modified and distributed by any means without the permission of the

author.

This cheatsheet has been made for the 12th graders' chemistry practical. Only the common tests used in school have been mentioned, certain parts were being omitted.\

Anions

● Some anions have not been included.

● Test mentioned next to group (or anion, for group III) is the

preliminary test; the ones mentioned under an anion are

confirmatory tests for it.

Group I (dilute H2SO4 group) – CO3

2- (carbonate), SO3

2- (sulphite), S2-

(sulphide), NO2

- (nitrite): Salt + dil H2SO4

1. No reaction: Group I anion not present. Continue to group II.

2. Carbonate: Colourless and odourless gas (CO2)

1. WE 1 + MgSO4 = white ppt

3. Sulphite: Colourless gas with pungent smell

1. WE + BaCl2 (aq) = white ppt soluble in dil HCl

2. WE + acidified K2Cr2O7

2 = sol 3 turns green

3. WE + acidified KMnO4 = pink colour of KMnO4 is discharged

4. Sulphide: Colourless gas with a smell of rotten eggs (H2S); turns

lead acetate paper black

1. Sodium nitroprusside test: WE + sodium nitroprusside 4 = purple

/ violet colour

2. Lead acetate test: WE + lead acetate 5 (aq) = black ppt

5. Nitrite: Pungent light brown gas

1. Starch-iodide test: WE + dil H2SO4 (or dil acetic acid); boil, then

add solid KI + fresh starch sol = deep blue colouration

1 Water extract – Made by taking a pinch of salt in a test tube and shaking it with water.

2 Potassium dichromate

3 Solution

4 Na2[Fe(CN)5NO]

5 Pb(CH3COO)2

Group II (conc H2SO4 group) – Cl- (chloride), Br- (bromide), I- (iodide),

NO3

- (nitrate), CH3COO- (acetate), C2O4

2- (oxalate): Salt + conc H2SO4

1. No reaction: Group II anion not present. Continue to group III.

2. Chloride: Colourless white pungent fumes (HCl); intensify when

glass rod dipped in NH4OH is brought near mouth of test tube

1. Silver nitrate test: WE + AgNO3 = white ppt soluble in NH4OH

2. Chromyl chloride test: Salt + solid K2Cr2O7 + 2-3 drops conc

H2SO4 = orange / red fumes of chromyl chloride 6

1. Vapours + NaOH (aq) = yellow solution

2. Yellow solution + acetic acid + lead acetate sol = yellow ppt

3. Bromide: Reddish brown vapour

1. Silver nitrate test: WE + AgNO3 (aq) = yellow ppt partially

soluble in NH4OH

2. Organic layer test: WE + CCl4 7 + 1 drop conc HNO3 8 = Upper

layer aqueous; lower layer organic of orange / brown colour

(bromine is soluble in non-polar solvent)

4. Iodide: Violet vapour

1. Silver nitrate test: WE + AgNO3 (aq) = yellow ppt insoluble in

NH4OH

2. Organic layer test: WE + CCl4 + 1 drop conc HNO3 = Upper layer

aqueous; lower layer organic of violet colour (iodine is soluble in

non-polar solvent)

5. Nitrate: Brown fumes with pungent smell, which intensify on

adding paper pellets (may need heating)

1. Brown ring test: WE + freshly prepared FeSO4 9 sol + 1 drop conc

HNO3 added along side of test tube = brown ring formed at

junction of sol and acid

6. Acetate: Pungent vapour with vinegar-like smell

1. Ester test: Salt + conc H2SO4 + ethanol = fruity smell of ester

2. Ferric chloride test: WE + FeCl3 (aq) = brick red colour

1. Add dil HCl = red colour disappears

2. Add water and boil = reddish brown ppt

7. Oxalate: Colourless gas with effervescence (CO + CO2)

1. Calcium chloride test: WE + acetic acid + CaCl2 (aq) + boil =

white ppt; ppt dissolves when dil HNO3 is added and warmed

2. Potassium permanganate test: Salt + dil H2SO4 + heat; then add

2-3 drops KMnO4 sol = pink colour of KMnO4 is discharged

6 CrO2Cl2

7 Carbon tetrachloride

8 HNO3 is added to act as oxidising agent

9 Ferrous sulphate

Group III anions (special group) – SO4

2- (sulphate), PO4

3- (phosphate):

No group reagent

1. Sulphate:

1. Barium chloride test: WE + BaCl2 (aq) = white ppt insoluble in

conc HCl

2. Lead acetate test: WE + lead acetate (aq) + acetic acid = white

ppt soluble in CH3COONH (ammonium acetate)

2. Phosphate:

1. Ammonium molybdate test: WE + dil HNO3 + ammonium

molybdate 10 + boil = crystalline canary yellow ppt

Cations

● All cations have not been mentioned.

● Group reagent is the one mentioned next to group cations.

● Test mentioned next to cation is the preliminary; ones under it are

confirmatory tests for it.

● When sulphate is detected, Ba2+, Ca2+, Pb2+, and Sr2+ are not

present as sulphates of these radicals are insoluble.

● When phosphate is detected, cations of group III and later are

absent.

Group 0 – NH4

+ (ammonium): No group reagent

1. Sodium hydroxide test: Salt + NaOH = pungent smelling gas; gives

white fumes when a glass rod dipped in conc HCl is brought near

mouth of test tube

2. Nessler's reagent 11 test: OS 12 + NaOH + Nessler's reagent =

Brown / yellow ppt

Group I – Pb2+ (lead): OS + dil HCl = white ppt; add water, boil, and

divide into three parts

1. Leave OS undisturbed = white crystals formed on cooling

2. Potassium iodide test: OS + KI = yellow ppt

3. Potassium chromate test: OS + K2CrO4 = yellow ppt

10 (NH4)2MoO4

11 K2HgI4

12 Original solution – Salt + acid + water

www.ankurb.info

Group II – Cu2+ (copper): OS + dil HCl + H2S = black ppt

1. Throw off extra sol, retain ppt, and dissolve in a few drops of conc

HNO3 = bluish green sol, ppt dissolves; divide into two parts

1. Part 1 + excess NH4OH = blue coloured sol

2. Potassium ferrocyanide test: Part 2 + acetic acid + K4[Fe(CN)6] =

reddish brown / chocolate coloured ppt (Note – this test is

difficult to get)

Group III – Fe2+, Fe3+ (iron), Al3+ (aluminium):

OS + solid NH4Cl + excess NH4OH

1. Fe2+ / Fe3+: Note – ferrous salts are green in colour, ferric salts are

brown in colour.

1. If ferrous salt has been given, convert to ferric: OS + conc HNO3

13 + heat = brown ppt; then do reaction with group reagent

2. Brown ppt + HCl; then divide into two parts

1. Potassium ferrocyanide test: Part 1 + K4[Fe(CN)6] = blue ppt /

colour

2. Potassium thiocyanate test: Part 2 + KCNS = blood red colour

2. Al3+: Gelatinous white ppt

1. Blue lake test: Retain ppt + dil HCl = clear sol

1. Sol + blue litmus and NH4OH (drop-by-drop) = blue colour

layer ('lake') floats over colourless sol

Group IV – Co2+ (cobalt), Ni2+ (nickel), Mn2+ (manganese), Zn2+ (zinc):

OS + solid NH4Cl + excess NH4OH + pass H2S gas

1. Co2+ / Ni2+: Black ppt; dissolve ppt in aqua regia 14 and evaporate

sol to dryness to get residue

1. Co2+: Blue residue; turns pink / purple when dissolved in water;

divide into two parts

1. Part 1 + dil acetic acid + KNO2 15 + warm = yellow ppt

2. Part 2 + ether (1 mL) + solid NH4CNS 16 = blue colour in ether

2. Ni2+: Yellow residue; turns green when dissolved in water; divide

into two parts

1. DMG 17 test: Part 1 + excess NH4OH + DMG = bright red ppt

2. Part 2 + NaOH + bromine water + boil = black ppt

2. Mn2+: Buff / skin colour ppt; divide into two parts

1. Part 1 + dil HCl + boil off H2S + NaOH = white ppt; which turns

black / brown on adding bromine water

13 Used as oxidising agent

14 Aqua regia is 3 parts conc HCl + 1 part conc HNO3

15 Potassium nitrite

16 Ammonium sulphocyanide

17 Dimethyl glyoxime reagent

2. Lead dioxide test: Part 2 + PbO2 + conc HNO3 + boil = after

cooling; pink colouration

3. Zn2+: Greyish white ppt; divide into two parts

1. Part 1 + excess NaOH = white ppt dissolves

2. Potassium ferrocyanide test: Part 2 + K4[Fe(CN)6] = white / bluish

white ppt

Group V – Ba2+ (barium), Sr2+ (strontium), Ca2+ (calcium):

OS + (NH4)2CO3 18 + NH4Cl + NH4OH = white ppt; add dil acetic acid,

divide sol into three parts and test for following IN ORDER

1. Ba2+: Part 1 + excess K2CrO4 19 (aq) = yellow ppt

2. Sr2+: Part 2 + (NH4)2SO4 20 (aq) = white ppt

3. Ca2+: Part 3 + (NH4)2C2O4 21 (aq) + NH4OH (only if nothing appears

at first) = white ppt

4. Flame test: Take salt and make a paste by mixing with conc HCl.

Take paste on tip of glass rod / platinum wire, and put in Bunsen

burner flame

1. Ba2+: Green flame

2. Sr2+: Crimson red flame

3. Ca2+: Brick red flame

Group VI – Mg2+ (magnesium): No group reagent

OS + NH4Cl + excess NH4OH + ammonium phosphate = white ppt

Coloured salts

Colour Inference

Blue Cupric salts

Green Hydrated nickel salts

Rose red Cobalt salts, HgI2

Light green Ferrous salts

Yellow / brown Ferric salts

Green / blue Hydrated copper salts

Deep blue Anhydrous cobalt salts

Pale pink Manganese salts

Dark green / purple Chromic salts

18 Ammonium carbonate

19 Potassium chromate

20 Ammonium sulphate

21 Ammonium oxalate