Page 246 - Primary Five Science

Test tube A

Presence of air (oxygen) and water rusted the nail

Test tube B

Air was prevented by a layer of oil. Although water was pre-

sent, the nail didn’t rust

Test tube C
Water was absorbed by a Calcium chloride. Therefore, none of

air or water was present and nothing happened to the nail

Conclusion

For rusting to occur, air and water must be present

Disadvantages of rusting

 It results in wearing of machinery (made of iron)

 It changes and spoils the colour of things

 Bolts become hard to unscrew after rusting

 Rusting makes cutting materials blunt.

 Keys fail to fit in padlocks after rusting

 Water containing rust is poisonous to drink