Chemical tests

Question 1

Give the test and result for hydrogen gas.

Answer 1

The test and result for hydrogen gas is a lit / burning splint makes a ‘squeaky pop’ sound.

Question 2

Give the test and result for oxygen gas.

Answer 2

The test and result for oxygen gas is a glowing splint relights.

Question 2

Give the test and result for carbon dioxide gas.

Answer 2

The test and result for carbon dioxide gas is limewater turns cloudy / milky.

Question 3

Give the test and result for chlorine gas.

Answer 3

The test and result for chlorine gas is that damp litmus paper turns red and then bleaches white.

Question 4

Give the test and result for ammonia gas.

Answer 4

The test and result for ammonia gas is using damp red litmus paper which will turn blue.

Question 5

True or False?

Chlorine is a colourless, pungent gas.

Answer 5

False.

Chlorine is a green pungent gas

Question 6

What is a flame test used for?

Answer 6

A flame test is used to identify metal ions by the colour of the flame they produce when heated.

Question 7

True or False?

The Bunsen burner flame should be on a blue flame for flame tests.

Answer 7

True.

The Bunsen burner flame should be on a blue flame for flame tests as this is the hottest flame.

Question 8

Give the flame colour produced by sodium ions.

Answer 8

The flame colour produced by sodium ions is yellow.

Question 9

Give the flame colour produced by copper(II) ions.

Answer 9

The flame colour produced by copper ions is blue / green.

Question 10

True or False?

The flame colour produced by potassium ions is pink.

Answer 10

False.

The flame colour produced by potassium ions is lilac.

Question 11

Give the flame colour produced by calcium ions.

Answer 11

The flame colour produced by calcium ions is orange-red.

Question 12

True or False?

The flame colour produced by lithium ions is red.

Answer 12

True.

The flame colour produced by lithium ions is red.

Question 13

Why is the nichrome wire first dipped in hydrochloric acid?

Answer 13

The nichrome wire is first dipped in hydrochloric acid to avoid contamination.

Question 14

Define the term cation.

Answer 14

A cation is a positively charged ion.

Question 15

What is the formula of an ammonium ion?

Answer 15

The formula of an ammonium ion is NH4+.

Question 16

What colour precipitate is formed when sodium hydroxide is added to a solution containing copper(II) ions?

Answer 16

The colour of the precipitate formed when sodium hydroxide is added to a solution containing copper(II) ions is blue.

Question 17

True or False?

Iron(III) ions form a green precipitate in the presence of sodium hydroxide.

Answer 17

False.

Iron(III) ions form a brown precipitate in the presence of sodium hydroxide.

Question 18

Describe a test for ammonium ions.

Answer 18

The test for ammonium ions is:

Add sodium hydroxide solution

If ammonium ions are present, ammonia gas is produced which turns damp red litmus paper blue.

Question 19

What colour precipitate is formed when sodium hydroxide is added to a solution containing iron(II) ions??

Answer 19

The colour of the precipitate formed by iron(II) ions in the presence of sodium hydroxide is green.

Question 20

Define the term anion.

Answer 20

An anion is a negatively charged ion.

Question 21

Describe the test and result for bromide ions.

Answer 21

The test and result for bromide ions is:

Add dilute nitric acid followed by silver nitrate solution

A cream precipitate is formed

Question 22

What is the formula of a carbonate ion?

Answer 22

The formula of a carbonate ion is CO32-

Question 23

Describe the test and result for carbonate ions.

Answer 23

The test for carbonate ions is:

Add dilute hydrochloic acid and test the gas produced by bubbling it through limewater.

If carbonate ions are present, carbon dioxide is produced which turns limewater cloudy.

Question 24

Describe the test and result for iodide ions.

Answer 24

The test and result for iodide ions is: Add dilute nitric acid followed by silver nitrate solution A yellow precipitate is formed

Question 25

True or False? Chloride ions give a white precipitate with acidified silver nitrate solution.

Answer 25

True. Chloride ions give a white precipitate with silver nitrate solution.

Question 26

True or False? To test for sulfate ions, acidified berylium chloride is used.

Answer 26

False. To test for sulfate ions, barium chloride is used

Question 27

Name the white precipitate formed during a positive test for sulfate ions.

Answer 27

The white precipitate formed during a positive test for sulfate ions is barium sulfate.

Question 28

When acidified silver nitrate solution is added to a sample containing bromide ions, a precipitate of silver bromide is formed. What is the state symbol for this precipitate?

Answer 28

The state symbol for the precipitate of silver bromide is s.

Question 29

Describe the chemical test for water.

Answer 29

Describe the chemical test for water.

Question 30

Define the term pure substance.

Answer 30

A pure substance consists of a single element or compound.

Question 31

Describe the physical test used to determine whether a sample of water is pure.

Answer 31

The physical test to determine whether a sample of water is pure is to check its boiling point which should be exactly 100 oC.

Question 32

What colour does anhydrous copper(II) sulfate turn in the presence of water?

Answer 32

Anhydrous copper(II) sulfate turns blue in the presence of water.

Question 33

True or False? Impurities tend to raise the boiling point of water.

Answer 33

True. Impurities tend to raise the boiling point of water.

Question 34

Name the piece of apparatus used to check the boiling point of water.

Answer 34

The piece of apparatus used to check the boiling point of water is a thermometer.

Question 35

True or False? Impurities tend to raise the melting point of water.

Answer 35

False. Impurities tend to lower the melting point of water.