CHEMICAL CHANGES

Question 1

What are the two ways you can test the ph of a solution

Answer 1

universal indicator and a ph probe

Question 2

what does a ph probe give you the ph as

Answer 2

an numerical value

Question 3

when acids dissolve in water what do they form

Answer 3

H+ ions

Question 4

when alkalis dissolve in water what do they from

Answer 4

OH- ions

Question 5

what is the neutralisation equation

Answer 5

acid + Base ——– salt + water

Question 6

acid + base =

Answer 6

salt + water

Question 7

neutralisation symbol equation

Answer 7

(H+) + OH- —— H2O

Question 8

what does an acid and an alkali make

Answer 8

water which is neutral

Question 9

when a acid neutralises a base the products are…..

Answer 9

neutral

Question 10

strong acids…

Answer 10

fully ionise in water

Question 11

in strong acids all acid particles….

Answer 11

dissociate to release H+ ions

Question 12

examples of strong acids

Answer 12

sulfuric acid, hydrochloric acid and nitric acid

Question 13

weak acids…

Answer 13

partially ionise in water

Question 14

in weak acids…. (particles)

Answer 14

only a small amount of acid particles dissociate to release H+ ions

Question 15

examples of weak acids

Answer 15

ethanoic, citric and carbonic

Question 16

symbol for hydrochloric acid

Answer 16

HCL

Question 17

symbol for nitric acid

Answer 17

HNO3

Question 18

symbol for sulfuric acid

Answer 18

H2SO4

Question 19

pH is a measure of….

Answer 19

the concentration of H+ ions

Question 20

acid + metal oxide =

Answer 20

salt + water

Question 21

acid + metal hydroxide =

Answer 21

salt + water

Question 22

acid + metal carbonate =

Answer 22

salt + water + carbon dioxide

Question 23

acid + metal base =

Answer 23

salt + water

Question 24

mnemonic for the reactivity series

Answer 24

Please       POTASSIUM
Stop          SODIUM
Calling      CALCIUM
Me            MAGNESIUM
A               ALUMINIUM
Careless   CARBON
Zebra       ZINC
Instead    IRON
Try           TIN
Learning LEAD
How       HYDROGEN
Copper   COPPER
Saves   SILVER
Gold     GOLD

Question 25

acid + metal =

Answer 25

salt + hydrogen

Question 26

metal + water =

Answer 26

metal hydroxide + hydrogen`

Question 27

what is oxidation in terms of oxygen

Answer 27

gain of oxygen

Question 28

what is reduction in terms of oxygen

Answer 28

loss of oxygen

Question 29

what metals can be extracted by reduction using carbon

Answer 29

metals below carbon in the reactivity series

Question 30

how are metals extracted from their ores by reduction with carbon

Answer 30

the ore is reduced as oxygen is removed from it, and carbon gains oxygen so is oxidised

Question 31

what metals can be extracted by using electrolysis

Answer 31

metals higher than carbon in the reactivity series

Question 32

what is oxidation in terms of electrons

Answer 32

oxidation is the loss of electrons

Question 33

what is reduction in terms of electrons

Answer 33

reduction is gain of electrons

Question 34

mnemonic for oxidation and reduction in terms of electrons

Answer 34

OILRIG | OXIDATION IS LOSS REDUCTION IS GAIN

Question 35

What is a displacement reaction

Answer 35

a more reactive metal will displace a less reactive metal from its compound

Question 36

where is lithium on the periodic table

Answer 36

underneath sodium

Question 37

what is an electrolyte

Answer 37

is a liquid or solution that can conduct electricity

Question 38

what are the two electrodes

Answer 38

anode and cathode

Question 39

where do the positive ions in an electrolyte move to? and what happens there

Answer 39

the cathode where they are reduced

Question 40

where do the negative ions in an electrolyte move to? and what happens there

Answer 40

the anode where they are oxidised

Question 41

in electrolysis of aqueous solutions what happens at the anode

Answer 41

if halide ions are present a halogen will be formed | if no halide ions are present oxygen will be formed

Question 42

in electrolysis of aqueous solutions what happens at the cathode

Answer 42

if the metal is more reactive than hydrogen ,, hydrogen will form if the metal is less reactive than hydrogen,, the metal will form

Question 43

at the cathode does it lose or gain electrons?

Answer 43

gain electrons

Question 44

at the anode does it lose or gain electrons?

Answer 44

lose electrons

Question 45

in half equations for redox reactions if the electrons are on the right hand side it is

Answer 45

oxidation

Question 46

in half equations for redox reactions if the electrons are on the left hand side it is

Answer 46

reduction

Question 47

at the anode is it oxidation or reduction

Answer 47

oxidation

Question 48

at the cathode is it oxidation or reduction

Answer 48

reduction

Question 49

Sodium is one of the most abundant metals on Earth. Explain, as fully as you can, why sodium was not extracted until 1807.

Answer 49

sodium is very reactive | have to use electrolysis to remove it,

Question 50

explain why an acid can be described as both strong and dilute

Answer 50

can be called strong acid because it is completlely ionised but can be called dilute because small amount of acid per unit volume