Chemistry Test on 27 Feb(Fri)

Test on Cations. - Study the proactical worksheet that we did last week(textbook page 175).

Vector Test on Monday, 23rd Feb!

Study on vector worksheets 1A and 1B, including triangle law.
4e2, u can do it if u wan...
God Bless!

Class QA results in lab

This is the result from test for Na+. Guess what is the name of the whote ppt?
Write out the equation if u can.












White ppt from test of Al3+. Whose sample is this? Who is the girl behind???
Write out the equation of this reaction?

Why Alloys?

Four reasons for making alloys :
•To improve the strength and hardness of metals,
•To improve the resistance of metals against corrosion,
•To improve the appearance of the metals,
•To lower melting point of the metal.

Properties of Metals

•Gold is attractive and used for jewellery
•Steel is an alloy of iron and made sharp for cutting
•Copper is good at conducting heat
•Iron is strong and has high tensile strength
•Tin cans do not corrode
•Aluminium is light and is used in aircraft construction


Physical Property & Link with Structure of Metals
1 malleable (easily bent) and ductile (easily stretched)
Reason: layers of metal atoms can slide over each other easily
2 high density
Reason: close packing of metal atoms
3 good conductors of heat and electricity
Reason: contain electrons which are free to move throughout the metal
4 high melting and boiling points
Reason: a lot of energy is required to weaken and break the strong bonds

Recycling of metals

Advantages
§metal ores are conserved, thus will last longer
§money is saved in the energy needed to extract new metals from ores
§unsightly scrap metal is removed from the environment

Disadvantages
§expensive to collect small bits of metal from many sources
§metal fumes produced in the melting of scrap metals during recycling can cause pollution

Extraction of iron

Important slides to memorise.
Extraction of iron.

Memorise the digram and the equations.

Write out the different processes at each stage.