You mods don't go merging my topic k, this is a doubt that I
wanna settle :D
Chemistry 5072 Paper 2
To cut it short, will platinum atoms EVER form platinum ions in
a normal situation (like not under 1000 atm and 3500 degrees
celsius la...)?
Because there was an electroplating question. It was coating an
iron cylinder (or smth like that) with aq zinc sulphate, and the
iron is -ve charged. So zinc ions in solution go and reduced there
form zinc right, then iron plated with zinc, ya simple to
understand right ;D
They asked why do we need to replace zinc brushes more
than platinum brushes. Because it's like electroplating,
the zinc "rod" is called a brush here, whereby zinc atoms will go
into the aq zinc sulphate solution, blah blah blah story...
So will platinum EVER be oxidised to platinum ions and go into
the aq zinc sulphate?
It's like using a platinum and iron rod in electroplating, then
the electrolyte is aq zinc sulphate.
I wrote, about the replacement thingy, "As zinc is more reactive
metal than platinum, zinc atoms will lose electrons to form zinc
ions MORE READILY than platinum atoms losing electrons to form
platinum ions, thus the zinc brush will become thinner more quickly
than platinum over time and not as efficient in apply aq zinc
sulphate onto the iron plate."
Meh, too kanchiong, all concepts went out of the window liao...
Should just write platinum is inert right... Btw the question is 2
marks.
Thanks for checking :D
EDIT: New doubt. A question wanted us to write the formula for
the amide and ester linkages... So draw structural formula or
write? And what is the formula?
Btw, they gave us the whole damn structural formula of nylon and
terylene, so I think if they want you to draw the amide and ester
linkages, a bit too give away liao lor...
The zinc brush contains the zinc ions which dissolve when the
electroplating is conducted. The zinc ions replace the zinc ions
from the aq zinc sulphate solution hence effective concentration
remains the same.
As the zinc brush loses zinc ions, it shrinks in size gradually.
Thus the brush needs to be replaced.