behavior and uses of metals

Question 1

stage 1

Answer 1

coke burns to give co2, blast of hot air starts the coke burning

Question 2

stage 1 reaction

Answer 2

c + o2 - co2
carbon is oxidised, highly exothermic, heat given out heats furnace

Question 3

stage 2

Answer 3

co2 is reduced to carbon monoxide, co2 reacts with more coke

Question 4

stage 2 reactions

Answer 4

c + co2 - 2co
carbon is reduced, endothermic, takes heat from furnace

Question 5

stage 3

Answer 5

carbon monoxide reduces iron III oxide to iron, extraction of metal occurs

Question 6

stage 3 reactions

Answer 6

fe2o3 + 3co - 2fe +3co2
iron oxide is reduced, iron trickles to the bottom, co is the reducing agent, co is reduced

Question 7

stage 4

Answer 7

slag is formed, calcium silicate forms slag which runs down the furnace and floats on the iron

Question 8

stage 4 reactions

Answer 8

caco3 -heat- cao + co2
limestone breaks down in the heat of the furnace- thermal decomposition

cao + sio2 - casio3
calcium oxide reacts with sand, main impurity in iron ore. sand is mostly silicon

Question 9

alloy

Answer 9

mixture of a metal with at least one other element

Question 10

alloy benefits

Answer 10

change properties to make it more useful

Question 11

brass

Answer 11

• copper and zinc
• used for ornaments, instruments and door knobs
• hard, doesnt corrode and attractive

Question 12

stainless steel

Answer 12

• iron, carbon, chromium and nickel
• used for cutlery and construction equipment
• hard, doesnt corrode and attarctive

Question 13

rusting

Answer 13

name given to the corrosion of iron (breakdown). iron reacts with water and oxygen to give hydrated iron III oxide

Question 14

rusting formula

Answer 14

4fe + 3o2 + 4h2o - 2feo3 + 2h2o

Question 15

prevention

Answer 15

covering the metal
sacrificial protection

Question 16

covering the metal

Answer 16

• paint
• grease
• plastic
• another metal

Question 17

sacrificial protection

Answer 17

cover the metal with zinc so it corrodes instead of iron or steel. this provides a layer of protection. zinc will corrode and the corrosion can be removed for it to corrode again

Question 18

aluminum

Answer 18

placed between zinc and magnesium on the reactivity series, ahead of carbon but unreactive. aluminum reacts readily with oxygen forming hard impenetrable oxide layer protecting the aluminum from further reaction

Question 19

displacement reactions

Answer 19

a more reactive metal will also displace a less reactive metal from a solution which contains the less reactive metal. the more reactive metal loses electrons to form positive ions.

Question 20

characteristics chemical properties of metals

Answer 20

a reactive metal is one that readily loses its valancy electrons to form compounds

Question 21

reactivity series

Answer 21

potassium
sodium
calcium
magnesium
aluminum
carbon
zinc
iron
tin
lead
hydrogen
copper
silver
gold
platinum

Question 22

metal extraction from ores

Answer 22

only a few unreactive metals are found ‘native’ i.e in their pure metal form. other metals are found in compounds and need to be extracted. this involves the reduction of the metal ions to give the metal

Question 23

reduction may occur via

Answer 23

• electrolysis
• reaction with carbon

Question 24

reaction with carbon

Answer 24

carbon will reduce metal oxides to the metal, if the metal is less reactive than carbon on the reacitivity series

Question 25

metal extractions

Answer 25

• carbon is used as a reference point to determine the method of extraction
• method of extraction is linked strongly to the reactivity series
• metals above carbon in the reactivity series must be extracted from their ores by electrolysis
• metals below carbon are reduced by carbon
• the least reactive metals occur in their native states and are separated by physical processes not chemical reactions