Chemical changes

Question 1

What is a pH scale?

Answer 1

measures how acidic or alkaline a solution is.

Question 2

The lower the pH means what?

Answer 2

The more acidic

Question 3

The higher the pH means what?

Answer 3

The more alkaline

Question 4

What pH does a Neutral substance have?

Answer 4

pH7

Question 5

How can you measure the pH of a solution?

Answer 5

Universal indicator

Question 6

How can you measure the pH electronically?

Answer 6

pH probe which is more accurate than an indicator

Question 7

What ions do Acids produce in aqueous solutions?

Answer 7

Hydrogen ions (H+)

Question 8

H+ + CL- form what?

Answer 8

HCI

Question 9

What are bases?

Answer 9

They are chemicals with a pH greater than 7 which can neutralise acids and produce salt and water

Question 10

What is a alkali?

Answer 10

It is a base that dissolves in water to forma solution greater than 7.

Question 11

Name an example of bases.

Answer 11

sodium hydroxide

Question 12

What ions do Alkali’s from in water?

Answer 12

OH- ions

Question 13

What does a green colour show on a pH scale

Answer 13

Neutral

Question 14

What do colours towards red show on a pH scale?

Answer 14

Show acidic solutions

Question 15

What do colours towards Purple show on a pH scale?

Answer 15

Alkaline solutions

Question 16

What do acids have a pH of?

Answer 16

Less than 7

Question 17

What are solutions with a pH of 7 show?

Answer 17

It is Neutral

Question 18

What do Alkaline’s have a pH of?

Answer 18

8-14

Question 19

What is the Neutralization equation?

Answer 19

Acid + base - Salt + water

Question 20

What is the symbol equation for Neutralization?

Answer 20

H+ + OH- - H2O

Question 21

In aqueous solutions what do acid molecules do?

Answer 21

They ionize (split) and release H+

Question 22

What are strong acids?

Answer 22

They fully ionize in aqueous solutions.

Question 23

Name 3 strong acids?

Answer 23

Sulfuric acid
Hydrochloric acid
Nitric acid

Question 24

How can you tell a reaction is fully ionized (strong acid)

Answer 24

Arrow goes in one direction

Question 25

What are weak acids?

Answer 25

They do not fully ionize in solution

Question 26

How can you tell a reaction has not fully ionized(Weak acid)?

Answer 26

Reversible arrow showing it is a reversible reaction.

Question 27

Name 3 weak acids

Answer 27

Ethanoic acid Citric acid Carbonic acid

Question 28

What does pH measure?

Answer 28

The concentration of Hydrogen Ions.

Question 29

Which has a Bigger pH weak acids or Strong acids?

Answer 29

Weak acids

Question 30

As the pH scale decreases by one unit, the concentration of hydrogen ions increase by how much?

Answer 30

10x

Question 31

What does the concentration of an acid tell you?

Answer 31

The amount of acid molecules in a given volume of solution.

Question 32

Hydrochloric acid + Copper oxide react together to from what?

Answer 32

Copper chloride and Water

Question 33

What do Hydrocholric acid produce ?

Answer 33

Chlorides

Question 34

What do Sulfuric acid produce ?

Answer 34

sulfates

Question 35

What do Nitric acid produce?

Answer 35

Nitrates

Question 36

An acid + Metal react together to form what?

Answer 36

Salt + water + Carbon dioxide

Question 37

Hydrochloric acid + Copper carbonate reacts together to form what?

Answer 37

Copper chloride + water + carbon dioxide

Question 38

Acid + Metal oxide react together to form what?

Answer 38

Salt + Water

Question 39

Acid + Metal hydroxide react together to form what?

Answer 39

Salt + water

Question 40

What do metals react with water to produce?

Answer 40

Metal hydroxide + Hydrogen

Question 41

When metals react what happens?

Answer 41

they lose electrons and form a positive ion

Question 42

Sodium + water reacts together to form what?

Answer 42

Sodium hydroxide and Hydrogen

Question 43

What are ores?

Answer 43

Metal compounds

Question 44

If a metal is less reactive than carbon what reaction can you carry out

Answer 44

Reduction of Carbon removing the compound from the metal leaving pure metals behind and give carbon dioxide.

Question 45

Why can't you use a metal more reactive than carbon when carrying out reduction?

Answer 45

Because carbon can only take oxygen away from metals which are less reactive than carbon

Question 46

What is Oil rig in terms of Electrons?

Answer 46

Oxidation is loss Reduction is gain

Question 47

What does Oxidation mean?

Answer 47

A gain of Oxygen e.g Magnesium is Oxidized to make magnesium oxide.

Question 48

What does Reduction mean?

Answer 48

A loss of Oxygen e.g. Copper oxide is reduced to copper

Question 49

What process does very reactive metals take?

Answer 49

Electrolysis

Question 50

What process does less reactive metals take?

Answer 50

Reduction

Question 51

What is a displacement reaction?

Answer 51

When a more reactive element takes the place of a less reactive element from its compound.

Question 52

In a displacement reaction the metal ion gains electrons meaning what?

Answer 52

Reduced

Question 53

In a displacement reaction if the metal ion loses electrons what does it mean?

Answer 53

It is Oxidized

Question 54

What is Electrolysis?

Answer 54

Splitting up with electricity

Question 55

What does Electrolysis work on?

Answer 55

A molten(Melted) ionic compound

Question 56

What is the negative electrode called?

Answer 56

Cathode

Question 57

What is the Positive Electrode called

Answer 57

Anode

Question 58

When the Positive ion moves to the electrolyte it moves to the negative electrode what happens to the electrons.

Answer 58

Gains electrons meaning it is reduced

Question 59

When the negative ion in the electrolyte moves to the positive electrode what happens to electrons.

Answer 59

Loses electrons meaning is Oxidised

Question 60

Why can molten ionic compounds be electrolysed?

Answer 60

because the ions can move freely and conduct electricity

Question 61

Why is the anode regularly replaced?

Answer 61

Made from carbon and the oxygen molecules produced at the anode reacts with carbon to make carbon dioxide gas.

Question 62

Why is electrolysis expensive?

Answer 62

Melting the compounds such as aluminium oxide requires a great deal of energy A lot of energy is required to produce the electric current.

Question 63

Water molecules ionize to form what?

Answer 63

Hydrogen and hydroxide

Question 64

When is Hydrogen produced at the cathode in aqueous solutions?

Answer 64

If the metal is more reactive than Hydrogen.

Question 65

At the anode what is usually produced?

Answer 65

Oxygen

Question 66

In electrolysis of sodium chloride produces chlorine gas why?

Answer 66

Because the chlorine ions are present in the solution