C5

Question 1

Why is electrolysis used to extract some metals?

Answer 1

If the metal reacts with carbon or is too reactive to be extracted using carbon

Question 2

What type of reaction happens when a compound breaks down?

Answer 2

Decomposition

Question 3

What type of indicator is used in a titration?

Answer 3

A single indicator because it has a sudden colour change (end-point)

Question 4

What is the reaction between an acid and alkali called?

Answer 4

Neutralisation reaction: Acid + Base –> Salt + Water

Question 5

What is an alkali?

Answer 5

An alkali is a base that dissolves in water to form a solution with a pH greater than 7. Alkalis form OH- ions in water.

Question 6

What is an acid?

Answer 6

An acid is a substance that forms aqueous solutions with a pH of less than 7. Acids form H+ ions in water.

Question 7

What is a weak acid?

Answer 7

A weak acid is partially ionised in aqueous solution

Question 8

What is a titration used for?

Answer 8

If the volumes of 2 solutions that react completely are known and the concentration of 1 solution is known, the concentration of the other solution can be calculated.

Question 9

What is a strong acid?

Answer 9

A strong acid is an acid that is completely ionised in aqueous solution

Question 10

What is a reaction that separates a metal from its oxide called?

Answer 10

A reaction that separates a metal from its oxide is called a reduction reaction

Question 11

What is a pipette used for?

Answer 11

To measure a fixed volume accurately

Question 12

What is a pH scale?

Answer 12

A pH scale is a measure of how acidic or alkaline a solution is

Question 13

What is a displacement reaction?

Answer 13

When a more reactive metal can displace a less reactive metal from a compound

Question 14

What is a burette used for?

Answer 14

To measure a variable/continuous volume

Question 15

What is a base?

Answer 15

A base is a substance greater than a pH of 7

Question 16

What happens when an acid reacts with a metal?

Answer 16

Acid + Metal —> Salt + Hydrogen

Question 17

What happens when an acid reacts with a metal oxide/hydroxide?

Answer 17

Acid + Metal Oxide/Hydroxide —> Salt + Water

Question 18

What do we call reactions which involve both oxidation and reduction reactions?

Answer 18

Redox reactions

Question 19

What do metals form?

Answer 19

Positive ions, they lose electrons. All elements in the reactivity series form positive ions.

Question 20

What are the products of the reaction of sodium and water?

Answer 20

Sodium Hydroxide + Hydrogen

Question 21

Steps of a titration

Answer 21

• alkali in burette
• acid in a conical flask measured out with 25cm^3
• add a few drops of indicator
• add alkali to acid until colour changes
• swirl conical flask
• add alkali drop wise towards the end
• note final burette reading
• repeat for accurate results

Question 22

Name an indicator suitable for a titration

Answer 22

Methyl orange (yellow in alkalis and red in acids)

Question 23

Name a strong acid

Answer 23

Hydrochloric acid, nitric acid, sulfuric acid

Question 24

Metal carbonates and metal hydroxides are examples of

Answer 24

Bases

Question 25

How can you form a metal hydroxide and hydrogen gas?

Answer 25

Metal + Water —> Metal Hydroxide + Hydrogen

Question 26

Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and dilute acid

Answer 26

• Pour sulfuric acid and excess magnesium oxide into a conical flask
• Heat it on a bunsen burner and stir with a glass rod
• After 3-4 minutes, filter out the excess magneisum oxide using a filter paper and a flask
• Boil the filtrate using an evaporating basin
• Move the bunsen burner in and out to make sure crystals form
• Leave to allow all water to evaporate in evaporating basin

Question 27

____ + __ __ —> Salt + Water + Carbon Dioxide

Answer 27

Acid + Metal Carbonate