C5 - Chemical Changes

Question 1

What happens when metals react with other substances

Answer 1

The metal atoms form positive ions

Question 2

What is the reactivity of a metal related to

Answer 2

To its tendency to form positive ions

Question 3

How can the metals be ordered by their reactions with water and dilute acid

Answer 3

They can be ordered in the reactivity series.

Question 4

What non-metals are often included in the reactivity series

Answer 4

Hydrogen and carbon

Question 5

What can happen when a more reactive metal reacts with a less reactive metal

Answer 5

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

Question 6

Order the reactivity series (which you are required to know)

Answer 6

potassium, sodium, lithium, calcium, magnesium, zinc, iron, copper

Question 7

What metals in the reactivity series react with water (fizz with cold water)

Answer 7

potassium, sodium, lithium, calcium, magnesium, (magnesium and higher)

Question 8

What metals in the reactivity series react with a dilute acid

Answer 8

potassium, sodium, lithium, calcium, magnesium, zinc, iron (above but not including copper)

Question 9

What gas is given off if metals react with water or dilute acids

Answer 9

Hyrdogen gas

Question 10

How are unreactive metals found (e.g gold)

Answer 10

In the earth as the metal itself

Question 11

How are more reactive (most) metals found

Answer 11

as compounds that require chemical reactions to extract the metal.

Question 12

How can Metals less reactive than carbon be extracted

Answer 12

Extracted from their oxides by reduction with carbon.

Question 13

What is oxidation

Answer 13

The loss of electrons

Question 14

What is reduction

Answer 14

Gain of electrons

Question 15

In this ionic equation which element has been oxidised and which reduced

Fe(s)+Cu^2+(aq) -> Fe^2(aq)+Cu(s)

Answer 15

Iron oxidised

Copper reduced

Question 16

What does the reaction between metal and an acid produce aswell as salt

Answer 16

Hydrogen gas

Question 17

What is a redox reaction

Answer 17

A reaction with involves oxidisation and reduction

Question 18

What is a salt

Answer 18

A compound formed when the hydrogen in an acid is wholly or partially replaced by metal or ammonium ions.

Question 19

How can salts be made

Answer 19

Reacting a suitable metal with an acid. The metal must be above hydrogen in the reactivity series, but not dangerously reactive

Question 20

What do all acid have

Answer 20

Hydrogen

Question 21

What determins the salt you make

Answer 21

The metal you use, as well as the acid

Question 22

What does the acid provide

Answer 22

The negative ions present in all salts

e.g sulfuric acid H^2SO^4 makes sulfates

Question 23

What is the reaction between a metal and an acid an example of

Answer 23

A redox reaction

Question 24

What is oxidised and what is reduced in a reaction between a metal and an acid

Answer 24

The metal atoms lose electrons and are oxidised, and the hydrogen ions from the acid gain electrons and are reduced

Question 25

What happens when a acid reacts with a base

Answer 25

A neutralisation reaction occurs

Question 26

Whta is produced in a reaction between an acid and a base

Answer 26

A salt and water

Question 27

What do the sum of the charges on the ions in a salt add up to

Answer 27

Zero, this enables you to work out the formula of salts, knowing the charges on the ions present

Question 28

How can a pure, dry sample of the salt made in a acid-base reaction canbe crytalised out of a solution

Answer 28

By evaporating off most of the water, and drying with filter papers if necessary

Question 29

What is needed when a soluble salt is prepared by reacting an alkali with an acid

Answer 29

An indicator, the experiment can then be repeated without the indicator to make a salt, then a pure, dry sample of its crystals prepared

Question 30

What is produced when a carbonate reacts with an acid

Answer 30

Produce a salt, water, and carbon dioxide gas

Question 31

How can you test for hydrogen

Answer 31

Squeaky pop test (lighted splint)

Question 32

How can you test for carbon dioxide

Answer 32

Turns lime water cloudy

Question 33

What do acids produce in aqueous solutions

Answer 33

Hydrogen ions (H+)

Question 34

What do aqueous solutions of alkalis contain

Answer 34

Hydroxide ions (OH-)

Question 35

What are bases

Answer 35

Substances that will neutralise acids

Question 36

What is an alkali

Answer 36

A soluble hydroxide | Alkali produce OH- (aq) ions when you add them to water

Question 37

What can the pH scale be used for

Answer 37

To show how acidic or alkaline a solution is

Question 38

What are solutions that have a pH value of: Less than 7 More than 7 7

Answer 38

Less than 7 - aicidc More than 7 - alkaline 7 - neutral solution

Question 39

In neutralisation reaction between an acid and an alkali, how is water produced

Answer 39

Hydrogen ions react with hydroxide ions | H+(aq) + OH-(aq) -> H^2O(l)

Question 40

How can you use the universal indictator

Answer 40

To find the pH of a solution. It is special indictor made from a number of dyes. It turns a range of colours as the pH changes.

Question 41

What happens to a strong acid (e.g hydrochloric acid) in a aqueous solution

Answer 41

Completely ionised

Question 42

What happens to a weak acid (e.g ethanoic acid) in a aqueous solution

Answer 42

Partially ionised

Question 43

For a given concentration of aqueous solutions, the stronger an acid....

Answer 43

The lower the pH

Question 44

What happens when the pH decreases by one unit

Answer 44

The hydrogen ion concentration of the solution increases by a factor of 10

Question 45

Why are some acids described as weak (e.g prpanoic acid), whilst other are described as strong (e.g nitric acid)

Answer 45

Nitric acid is a strong acid because it will completely ionise in solution. This means it will split into positive H+ and negative H- ions. While, propanoic acid don't release H+ ions into the solution.

Question 46

Why is it possible to have very dilute solution of a strong acid with a higher pH value than a concentrated solution of a weak acid

Answer 46

This because the strong acid splits up into positive and negative hydrogen ions. While, the weak acids don't split up. It is reversable with a weak acid