metals

Question 1

Which metals are classes and base metals because they are corroded by air

Answer 1

Ag, Au Hg

Question 2

how do you convert sulfides to oxides

Answer 2

roast the ore in air. SO₂ is produced

Question 3

what problem doesn roasting cause

Answer 3

air pollution as sulphur dioxide is produced

Question 4

why cant carbon be used to reduce sulfide ores

Answer 4

CS doesnt exist and CS₂ isnt exothermic enough

Question 5

what is smelting

Answer 5

production of a metal from its ore by chemical reduction

Question 6

what reducing agent is used in smelting

Answer 6

usually C or CO

Question 7

describe the conditions needed to smelt copper

Answer 7

1084 degrees in a pottery kiln

Malachite + Charcoal + Fe oxide reflux to remove silica

Question 8

what is bronze made out of and what other copper alloys are there

Answer 8

Bronze is lead and copper - but these are soft metals

copper and arsenic and tin alloys

Question 9

what is brass made out of

Answer 9

copper and zinc

Question 10

how is brass made

Answer 10

heating copper and the zinc ore, the ore is reduced and zinc reacts with copper.

Question 11

Why cant zinc be smelted

Answer 11

cannot be reduced with C until a temp over 1000 degrees is used but zinc will be vapourised at this temp and is readily oxidised.

Question 12

decribe the process of Fe smelting

Answer 12

Charcoal and Fe ore. This is done at temps below the mp of iron. Molten slag runs out and CO reduces the ore to solid iron

Question 13

How can iron be made more malleable

Answer 13

Heating in air to 800 -900 degrees or by pudding ie stirring molten cast iron to remove some of the C.

Question 14

In a blast furnance what do C and CO₂ combine to give

Answer 14

CO which is the reducing agent.

Question 15

If a line for a particular oxide intersects with one of the oxdiation of carbon, what does this show

Answer 15

At or above this temperature the metal oxide can be reduced by C

Question 16

when do metals burn

Answer 16

if gibbs is large and negative then this is thermodynamically favourable

Question 17

what is role of CaCO₃ in the blast furnance

Answer 17

CaCO₃ —> CaO + CO₂

CaO + SiO₂ —> CaSiO₃

reacts with silicia to form a silica slag

Question 18

what is wrought iron

Answer 18

Pure iron with a little C

Question 19

what is pig iron

Answer 19

raw iron straight from the blast furnance

Question 20

What is Cast iron

Answer 20

contains C and Si, made by melting pig iron

Question 21

What is steel

Answer 21

alloy of iron and C

Question 22

how do you make steel

Answer 22

Add C to pure iron. Heat with charcoal for a week

Question 23

what is crucible steel

Answer 23

wrought iron is heated with charcoal at 1550 degress for up to 3-4 days

Question 24

what is the bessemer proccess

Answer 24

air is blown on molten pig iron reducing the C content for about half an hour. Fe oxidised to and reacts with impurites to give a slag. C —> CO

Question 25

what are the basic and acidic condtions in the bessemer process

Answer 25

Acidic - converter lined with silicia clay bricks.

Basic - MgO or dolomite lined and lime added to remove phosphate

Question 26

what is the basic oxygen process and explain the advantages over this than the bessemer process

Answer 26

oxygen blown into 280 tonnes of molten iron. This is better at removing impurities and is more controlable

Question 27

How is stainless steel made

Answer 27

contains Cr and Ni. Cr forms a passivating invisible layer fo CrO₂ on the surface.

Question 28

what is sodium and how is it stored

Answer 28

Soft metal and in oil

Question 29

How is Na produced

Answer 29

electrolysis of NaCl or Mixing it witl CaCl₂

Na and Na-Ca alloy at cathode and Chlorine at anode.

Question 30

why cant K be made in a downs cell via electroylsis

Answer 30

K is too soluable in KCl

Vapourises at temperature of reaction

Question 31

How is K obtained

Answer 31

Reduce with NaCl and distill K off

Question 32

How is copper electrofined

Answer 32

At anode there are slabs of unpure Cu and at cathodes are thin sheets of Cu. Electrolyte is CuSO₃. At anode Cu²⁺ produced and at cathode Cu ions reduced to pure Cu

Question 33

How is Ni purified

Answer 33

Sulfide ore is roasted and reduced with C

Question 34

How is pure Ni obtained

Answer 34

Crude metal is cast into anodes and NiCl₂ and NiSO₄ are the electrolyte. Impure Ni dissolves at anode and reappears pure at Cathode.

Question 35

What is the Mond Nickel process and what problem is there with this process

Answer 35

Ni(CO)₄ is a volatile liquid and can be purified by distillation. The compound thermally decomposes to Ni and CO. The nickel complex is extremely toxic.

Question 36

How can a purified CO be obtained from Fe(CO)₅

Answer 36

Distilliation and then this thermally decomposes to Fe and purified CO. This is extremely toxic

Question 37

what process is rusting

Answer 37

electrochemical and requires Fe, water and oxygen

Question 38

outline the simple process of rusting

Answer 38

Oxidation of Fe to Fe²⁺ and then oxidation of Fe²⁺ to Fe³⁺which ppt out as a hydrate

Question 39

How can rusting be stopped

Answer 39

By preveting water from getting on surface eg by coating or oiling the surface.
cover it with a metal that will form a passivating layer eg zinc or tin plating.
Use a sacrificial anode of second metal in electrochemical contact with iron eg Zn or Mg