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some1 pls explain : Q 31 paper 1 nov 07
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Do we need to remember the colours of some compounds like FeSO4, CuO, BaSO4 etc.?
Firstly, hydrogen is a reducing agent and can reduce compounds of metals less reactive than it.thanks for explaining. one more pls: Q 28 http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s07_qp_1.pdf
not really memorize, but u can guess them like most metal oxides are dark in colour (CuO Fe2O3), FeSO4 should be green as the test for Fe2+ is green ppt,Do we need to remember the colours of some compounds like FeSO4, CuO, BaSO4 etc.?
yes...u have to learn the colour of halogens in aqueous compounds...in displacement reactions for halogen, is there always a colour change? if yes, it means that we have to memorize all the colours of hologens?
do u know the colours changes?...can u post the important ones pls?yes...u have to learn the colour of halogens in aqueous compounds...
In displacement reactions for halogens, the colour change to the colour of more reactive halogen.do u know the colours changes?...can u post the important ones pls?
thanks surely this helps.In displacement reactions for halogens, the colour change to the colour of more reactive halogen.
Flourine is a pale yellow gas at rtp
Chlorine is a greenish gas at rtp
Bromine is a reddish liquid at rtp
Iodine is black solid at rtp
Astantine is a shiny black solid at rtp
Example: 2KBr + Cl2 = 2KCl + Br2(aq) .... solution turns red
2KI + Br2 = 2KBr + I2(aq) .... solution turns *brown*
*** iodine forms brown solution in water and purple vapour when heated .
hope it helps
For cations, learn the tests for iron (both oxidation state), copper(II), aluminium (which is the same as Pb), Zinc, calcium and ammonium ionsdo we need to learn the tests for Ba2+ Ca2+ Pb2+ and I- Br- ions...these are not seen often in past papers?
please suggest me a good chemistry teacher ........I am gonna fail it really bad
well....for o level chemistry, our coursebooks are sufficient...besides, to me, this is the easiest science sub...well i was facing the same problem few weeks ago but someone suggested me PACANS. i don't know its a good institute or not for other subjects but for chemistry there's a Female teacher. Her way of teaching is quiet good and i am happy to say that i am now 80% prepared for chemistry paper.
check this out, sort out ur problems from the detailed syllabus fragments starting page 10 and share it here, sm1 might helpplease suggest me a good chemistry teacher ........I am gonna fail it really bad
good job! thanksIn displacement reactions for halogens, the colour change to the colour of more reactive halogen.
Flourine is a pale yellow gas at rtp
Chlorine is a greenish gas at rtp
Bromine is a reddish liquid at rtp
Iodine is black solid at rtp
Astantine is a shiny black solid at rtp
Example: 2KBr + Cl2 = 2KCl + Br2(aq) .... solution turns red
2KI + Br2 = 2KBr + I2(aq) .... solution turns *brown*
*** iodine forms brown solution in water and purple vapour when heated .
hope it helps
is this included in our syllabus? ....ozone prevent harmful rays...(b) O3 + Cl2 = Cl2O + O2 (unsure)help please:
(a) why ozone is important in terms of human health? [2]
(b) write the reaction for the conversion ozone to oxygen by CFC?
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