Topic 4 - Chemical Changes (No Pracs)

Question 1

If a solution is acidic, is its pH low or high

Answer 1

Low

Question 2

If a solution of alkali is its pH low or high

Answer 2

High

Question 3

What’s the pH of a neutral solution

Answer 3

7

Question 4

What are some ways to measure the pH of a solution

Answer 4

• indicators
• a pH probe

Question 5

What ions do acids form in water

Answer 5

H+

Question 6

In neutralisation what is a base

Answer 6

A substance with a pH greater than 7

Question 7

What ions do alkalis form in water

Answer 7

OH-

Question 8

What’s the general equation for neutralisation

Answer 8

Acid + base > salt + water

Question 9

What are titrations used for

Answer 9

They are method of analysing concentrations of solutions

Question 10

What are strong acids

Answer 10

Acids that ionise completely in water - all acid particles dissociate to release H+ ions

Question 11

What are weak acids

Answer 11

Acids that do not fully ionise in solution

Question 12

Is the ionisation of weak or strong acids a reversible reaction

Answer 12

Weak

Question 13

Which are more reactive strong or weak acids

Answer 13

Strong

Question 14

Why are strong acids more reactive

Answer 14

Reactions of acids involve the H+ ions reacting - strong acids have a higher concentration of H+ ions

Question 15

For every decrease of 1 on the pH scale what happens to the concentration of H+ ions

Answer 15

It increases by a factor of 10

Question 16

What happens to a the pH of a acid if you increase the concentration

Answer 16

The pH will decrease

Question 17

What will reacting an acid with a metal oxide or a metal hydroxide form

Answer 17

A salt and water

Question 18

What will a reaction of an acid and a metal carbonate form

Answer 18

Salt + water + carbon dioxide

Question 19

What the mnemonic for the reactivity series

Answer 19

Peter said look calumn, my car zooms into hot countries

Question 20

What do you get if you react an acid with a metal

Answer 20

Salt + hydrogen

Question 21

How does reacting metals with acids show us their reactivity

Answer 21

The more reactive the metal the faster the reaction will go - measured by the rate of hydrogen bubbles given off, temperature change etc

Question 22

What do you get if you react a metal with water

Answer 22

Metal hydroxide + hydrogen

Question 23

Will all metal react with water

Answer 23

No - less reactive metals zinc, iron, and copper won’t

Question 24

What time of reaction is the formation of metal ores

Answer 24

Oxidation

Question 25

What type of reaction is an extraction of metal from an ore

Answer 25

Reduction

Question 26

What metals can be extracted using carbon

Answer 26

Those below carbon in the reactivity series

Question 27

How are metals above the carbon in the reactivity series extracted

Answer 27

Using electrolysis

Question 28

Why are some metals in the earth as the metal itself

Answer 28

They are so unreactive

Question 29

What’s a redox reaction

Answer 29

When electrons are transferred - reduction and oxidation are happening at the same time