C5 - chemical changes

Question 1

what are ores

Answer 1

rocks from which it is economical to extract the metals they have

Question 2

what happens to many metals in ores

Answer 2

they become oxidised

Question 3

how do you extract metals from oxides

Answer 3

reduce (remove the oxygen) the metal oxides

Question 4

what is the reactivity series

Answer 4

a list of metals in order of their reactivity with most reactive at the top and least at the bottom

Question 5

what are the two ways metal reactivity is ordered

Answer 5

reaction with water
reaction with a dilute acid (when reaction with water is slow)

Question 6

what is the full reactivity series

Answer 6

potassium
sodium
lithium
calcium
magnesium
aluminium
(carbon)
zinc
iron
tin
lead
(hydrogen)
copper
silver
gold

Question 7

how do potassium, sodium, lithium, and calcium react with water

Answer 7

fizz, give off hydrogen gas, leave an alkaline solution of metal hydroxide

Question 8

how do magnesium, aluminium, zinc and iron react with water

Answer 8

very slow reaction

Question 9

how do tin and lead react with water

Answer 9

slight reaction with steam

Question 10

how do copper silver and gold react with water

Answer 10

no reaction at all

Question 11

how do potassium sodium and lithium react with dilute acid

Answer 11

explode

Question 12

how do calcium magnesium aluminium zinc tin and iron react with dilute acid

Answer 12

fizz
give off hydrogen gas
form a salt

Question 13

how do tin and lead react with dilute acid

Answer 13

react slowly with warm acid

Question 14

how do copper silver and gold react with dilute acid

Answer 14

no reaction

Question 15

define a displacement reaction

Answer 15

a more reactive metal will displace a less reactive metal from an aqueous solution of one of its salts

Question 16

what does an ionic equation show

Answer 16

only the atoms and ions that change in a reaction

Question 17

what is oxidation

Answer 17

the loss of electrons

Question 18

what is reduction

Answer 18

the gain of electrons

Question 19

what does extracting a metal depend on

Answer 19

how easy it is to extract
how much metal the ore contains
the changing demands for the particular metal

Question 20

why do we often use carbon to extract some metal oxides

Answer 20

it is more reactive than the metals

Question 21

what is the word equation for the reaction of carbon with a metal oxide

Answer 21

metal oxide + carbon -> metal + carbon dioxide

Question 22

why is gold often found in its native state

Answer 22

because it’s incredibly unreactive

Question 23

how are metals extracted that are more reactive than carbon

Answer 23

by electrolysis of their molten metal compound

Question 24

what is a salt

Answer 24

a compound formed when the hydrogen atom is wholly or partially replaced by metal (or ammonium) ions

Question 25

what is the word equation for the production of salts

Answer 25

metal + acid -> salt + hydrogen

Question 26

why are alkali metals never added to acid

Answer 26

the reaction would be too violent to be carried out safely

Question 27

what salts are formed when you react a metal with HYDROCHLORIC ACID

Answer 27

chlorides (containing Cl- ions)

Question 28

what salts are formed when you react a metal with SULFURIC ACID

Answer 28

sulfates (containing SO4^2- ions)

Question 29

what salts are formed when you react a metal with NITRIC ACID

Answer 29

nitrates (containing NO3- ions)

Question 30

what is a redox reaction

Answer 30

a reaction where both oxidation and reduction take place

Question 31

how is the reaction between a metal and an acid a redox reaction

Answer 31

metal ions lose electrons (oxidised) hydrogen ions from acid gain electrons (reduced)

Question 32

what are bases

Answer 32

compounds that can neutralise acids

Question 33

what is the word equation for neutralisation

Answer 33

acid + base -> salt + water

Question 34

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

Answer 34

0

Question 35

how would you collect a pure dry sample of crystals of a salt

Answer 35

carry out titration with indicator run that volume of acid into solution but without indicator crystallise and dry the crystals of the salt

Question 36

what is the word equation for the reaction of an acid with a carbonate

Answer 36

acid + carbonate -> salt + water + carbon dioxide

Question 37

what are soluble hydroxides called

Answer 37

alkalis

Question 38

what are bases

Answer 38

substances that can neutralise acids

Question 39

what colour do alkalis go (using a universal indicator)

Answer 39

blue-purple

Question 40

what colour do acids go (using a universal indicator)

Answer 40

red-yellow

Question 41

what are carboxylic acids

Answer 41

weak acids

Question 42

what is hydrochloric acid

Answer 42

a strong acid

Question 43

what happens to hydrogen ion concentration when ph decreases by one unit

Answer 43

the hydrogen ion concentration increases by a factor of 10 (one order of magnitude)