Chemical Tests

Question 1

Flame Test Colour of Li

Answer 1

Red

Question 2

Flame Test Colour of Na

Answer 2

Yellow

Question 3

Flame Test Colour of K

Answer 3

Lilac

Question 4

Flame Test Colour of Rb

Answer 4

Red

Question 5

Flame Test Colour of Cs

Answer 5

Blue

Question 6

Flame Test Colour of Mg

Answer 6

White

Question 7

Flame Test Colour of Ca

Answer 7

Brick Red

Question 8

Flame Test Colour of Sr

Answer 8

Crimson

Question 9

Flame Test Colour of Ba

Answer 9

Green

Question 10

Test for Chloride Ions

Answer 10

Add HNO₃ and AgNO₃.
Positive Result: White precipitate that dissolves in dilute NH₃

Question 11

Test for Bromide Ions

Answer 11

Add HNO₃ and AgNO₃.
Positive Result: Cream precipitate which dissolves in conc. NH₃

Question 12

Test for Iodide Ions

Answer 12

Add HNO₃ and AgNO₃.
Positive Result: Yellow precipitate that does not dissolve in NH₃

Question 13

Test for NH₄⁺ Ions

Answer 13

Add NaOH and gently heat in a test tube. Test to see if ammonia gas is given off using damp red litmus paper.

Question 14

Test for CO₃^2- or HCO₃^- Ions

Answer 14

Add dilute HCl and check for fizzing. Run the gas through limewater and the positive result is it turning cloudy

Question 15

Test for SO₄^2- Ions

Answer 15

Add BaCl₂.
Positive Result: White precipitate

Question 16

Tests for Alcohols (3)

Answer 16

Add PCl₅.
Positive Result: Steamy fumes (HCl) given off.

Add Sodium.
Positive Result: Fizzing.

Add carboxylic acid with conc. H₂SO₄
Positive Result: Sweet smell.

Question 17

Test for Alkenes or Phenol

Answer 17

Add bromine water.
Positive Result: Orange to Colourless

Question 18

Test for Halogenoalkanes

Answer 18

Add ethanol, then aqueous NaOH, then do the test for halide ions

Question 19

Test for Carbonyls

Answer 19

Add 2,4-DNPH.
Positive Result: Orange precipitate forms

Question 20

Tests for Aldehydes (4)

Answer 20

Add Tollen’s Reagent and warm.
Positive Result: Silver mirror forms.

Add Fehling’s Solution and warm.
Positive Result: Blue to Brick-Red Precipitate

Add acidified K₂Cr₂O₇ and reflux
Positive Result: Orange to green.

Add acidified KMnO₄ and reflux
Positive Result: Purple to colourless

Question 21

Test for Ethanal or Methyl Ketones

Answer 21

Heat with I₂ in the presence of an alkali (NaOH)
Positive Result: Yellow Precipitate (CH₃I) and Antiseptic Smell

Question 22

Tests for Carboxylic Acids (4)

Answer 22

Turns blue litmus paper red.

Add a carbonate.
Positive Result: Fizzing. Limewater turns cloudy.

Add PCl₅.
Positive Result: Steamy fumes (HCl) given off

Alcohol with conc. H₂SO₄
Positive Result: Sweet smell.

Question 23

Test for Benzene

Answer 23

Burns with a sooty flame.

Does not react with bromine water at room temperature

Question 24

Tests for 1° and 2° Alcohols (2)

Answer 24

Add acidified K₂Cr₂O₇ and reflux
Positive Result: Orange to green.

Add acidified KMnO₄ and reflux
Positive Result: Purple to colourless

Question 25

Test for Amines

Answer 25

Turns red litmus paper blue.

Question 26

Test for Acyl Chlorides

Answer 26

Add water.
Positive Result: Steamy fumes.