Qualitative Tests

Question 1

What gas produces a squeaky pop when a burning splint is applied?

Answer 1

Hydrogen gas (H)

Question 2

What is the observation when oxygen gas (O2) is tested with a glowing splint?

Answer 2

It relights

Question 3

What happens to damp blue litmus paper when chlorine gas (Cl) is applied?

Answer 3

Turns red and then is bleached white

Question 4

What test is used to identify carbon dioxide gas (CO2)?

Answer 4

Bubble the gas through limewater (aqueous calcium hydroxide solution)

Question 5

What is the expected observation when carbon dioxide gas is bubbled through limewater?

Answer 5

Goes from a colourless solution to a white precipitate

Question 6

What occurs with prolonged exposure of carbon dioxide in limewater?

Answer 6

Formation of a colourless solution

This is due to the dissolution of calcium carbonate.

Question 7

Fill in the blank: The observation for hydrogen gas when a burning splint is applied is a _______.

Answer 7

squeaky pop

Question 8

True or False: Chlorine gas will turn damp blue litmus paper red and then bleach it white.

Answer 8

True

Question 9

What is the chemical formula for ammonia gas?

Answer 9

NH3

Question 10

What should be done to test for hydrogen chloride?

Answer 10

Expose to a glass rod dipped in concentrated ammonia solution or stopper from bottle of concentrated ammonia solution

Question 11

What should be done to test for ammonia gas?

Answer 11

Expose to a glass rod dipped in concentrated hydrochloric acid or stopper from bottle of concentrated hydrochloric acid

Question 12

What is produced when hydrochloric acid and ammonia gas come into contact?

Answer 12

White fumes/smoke/solid (ammonium chloride)

Question 13

True or False: Ammonium chloride is formed from the reaction of ammonia and hydrogen chloride.

Answer 13

True

Question 14

Fill in the blank: The reaction between hydrogen chloride and ammonia produces _______.

Answer 14

ammonium chloride

Question 15

What is the purpose of the flame test?

Answer 15

To identify metal cations

Question 16

What is the first step in conducting a flame test?

Answer 16

Take a piece of nichrome wire and dip it into concentrated hydrochloric acid

Question 17

What is the second step in conducting a flame test?

Answer 17

Dip the nichrome wire into the sample

Question 18

What type of flame is used in a flame test?

Answer 18

Blue Bunsen burner flame

Question 19

What colour is observed when lithium cations are present

Answer 19

Crimson

Question 20

What colour is observed when potassium cations are present

Answer 20

Lilac (pink through cobalt glass)

Question 21

What colour is observed when sodium cations are present

Answer 21

Yellow/orange

Question 22

What colour is observed when calcium cations are present

Answer 22

Brick red

Question 23

What colour is observed when copper cations are present

Answer 23

Blue-green

Question 24

What colour is observed when barium cations are present

Answer 24

Green

Question 25

What test method is used to identify sulfate ions?

Answer 25

Add a few drops of barium chloride solution or barium nitrate solution to a sulfate solution. ## Footnote Barium ions react with sulfate ions to form a precipitate.

Question 26

What observation indicates the presence of sulfate ions?

Answer 26

A white precipitate of barium sulfate. The chemical reaction is Ba²⁺(aq) + SO4²⁻(aq) → BaSO4(s).

Question 27

Fill in the blank: The reaction for sulfate detection is Ba²⁺(aq) + SO4²⁻(aq) → _______.

Answer 27

BaSO4(s) ## Footnote This indicates that barium sulfate is formed as a solid precipitate.

Question 28

What are the halide ions mentioned?

Answer 28

Cl-, Br-, I-

Question 29

What is the reaction that occurs when silver nitrate is added to a solution of chloride in dilute nitric acid?

Answer 29

A white precipitate of silver chloride forms. ## Footnote The chemical reaction is Ag+(aq) + Cl-(aq) → AgCl(s).

Question 30

What color precipitate forms when silver nitrate is added to a solution of bromide?

Answer 30

A cream precipitate of silver bromide forms. This precipitate is insoluble in dilute ammonia but soluble in concentrated ammonia.

Question 31

What color precipitate forms when silver nitrate is added to a solution of iodide?

Answer 31

A yellow precipitate of silver iodide forms. This precipitate does not dissolve in either dilute or concentrated ammonia solution.

Question 32

What is the test for iodine using starch?

Answer 32

Addition of aqueous starch to iodine solution results in a blue-black/black-blue solution.

Question 33

What is the test for carbonate ions?

Answer 33

Add dilute hydrochloric acid and bubble the gas produced through colourless limewater. The limewater will turn from colourless to milky (white precipitate)