can't get a question in nov 2007 chemistry,,,any help plz ?

[Dooouuu]

hey
http://www.xtremepapers.me/CIE/index.ph ... 7_qp_6.pdf

question 2)C .. i & ii

i can't understand the answer...........how is the acids and the salts increase rate of rusting and here in this question the markscheme said " NO EFFECT " ??? :fool:

 

[basimnazir]

Re: can't get a question in nov 2007 chemistry,,,any help pl

2.c.i. The formation of the rust would be much slower as the surface area should be less during rusting, and not more. The iron nail has more surface area and the rate of rusting is reduced.
2.c.ii. Salt doesn't effect the rate of rusting.

 

[Cozmo35d]

Re: can't get a question in nov 2007 chemistry,,,any help pl

for c)i) Surface area has decreased, reaction becomes slower, and for c)ii) Dirty water is used, this will speed the rusting reaction.

I hope this helped you & good luck with your exam tomorrow :good:

Edit: Basimnazir's answer for c)ii) is right, mine is wrong.

 

[Dooouuu]

Re: can't get a question in nov 2007 chemistry,,,any help pl

2.c.i. The formation of the rust would be much slower as the surface area should be less during rusting, and not more. The iron nail has more surface area and the rate of rusting is reduced.
2.c.ii. Salt doesn't effect the rate of rusting.

it was written in my studying notes that rate of rusting increase with the increase of the salts and acids :unknown:

 

[basimnazir]

Re: can't get a question in nov 2007 chemistry,,,any help pl

Well my book (written by the examiners and yes the latest one) had this written up.