c15

Question 1

what is corrosion

Answer 1

the destruction of materials by chemical reactions with substances in the environment

Question 2

what is rusting and what is required for metals to rust?

Answer 2

a type of corrosion. both air and water are necessary for iron to rust.

Question 3

how can corrosion be prevented?

Answer 3

by applying a coating that acts as a barrier like greasing, plating or electroplating

Question 4

how do barrier methods prevent corrosion

Answer 4

it prevents the metal to come into contact with oxygen and water.
aluminium has an oxide coating that protects the metal from further corrosion

Question 5

what is galvanising or sacrificial protection

Answer 5

• metal like iron can be prevented from rusting by being coated by a metal with a higher reactivity like zinc
• the higher reactivity metal will corrode and it will lose electrons more easily

Question 6

what is bronze an alloy of

Answer 6

copper and tin
usd for ornaments and medals

Question 7

what is brass an alloy of

Answer 7

copper and zinc
used for plumbing and carpentry

Question 8

what metals are used in alloys with gold in jewellery

Answer 8

• silver, copper and zinc
• 24 carat gold is pure gold. 18 carat is 75% gold

Question 9

what is steel

Answer 9

alloys of iron that contains specific amounts of carbon and other metals

Question 10

high carbon steel

Answer 10

it is strong but brittle

Question 11

low carbon steel

Answer 11

softer and more easily shaped

Question 12

stainless steel

Answer 12

• contains chromium and nickel and is hard and resistant to corrosion

Question 13

what is most of the glass we use made from?

Answer 13

soda lime glass - made by heating a mixture of sand, sodium carbonate and limestone

Question 14

what is borosilicate glass

Answer 14

it is made from sand and boron trioxide
- melts at a higher temperature than soda lime glass