Copper tubes in air conditioners quick questionsneed ur help ly

[KAS90]

Copper tubes in air conditioners...quick questions..need ur help urgently..

hey there..
I have an assignment where I have to choose a material and research about..
anyway, I chose to talk about copper tubes in air conditioners..My question is..
what is the function of this tube?
What is the most distinctive characteristic/property that makes manufacturers choose copper to be used in the manufacturing of these tubes?
Finally, I read that an amount of phosphorus(P) or silver(Ag) is added to the copper.. Why is phosphorus/silver added to the copper?
I appreciate ur help coz by answering these questions I'll understand so many things, and ill be able to finish my assignment..
Need ur help! please..!
Thanks in advance..

 

[KAS90]

hey again..
no 1 has ne idea?
I came 2 know that brass is used in the air conditioners..but what is the tube or fitting the aircondiotioner used 4? what's it's function?
and is there a kind of test that tests the corrosive property of an alloy or element?
I really neeeed ur help..pllllz..
just 4 these 2 questions..4get about the one above!
thanx again in advance..