Qualitative Analysis for Chemistry Practials
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My teacher has went through it with me....
Mainly it's to judge which colour will appear going by theory. For eg Solution A + Solution B when added together, i should be be expecting a blue-green solution bla bla
But i just dont get it leh...Im just tio stun how come they can predict all these colours 1..
So can sme pls explain to me?
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u haf to see the products of the reaction. different products haf different colours(mainly transitional metal ions). the common ones r Cu2+, Cu3+, Fe3+, Fe2+....otherwise is according to acidity or oxidation.
acidity:depending on indicator used, different indicators haf different colour changes. for example, phenolthalein will b pink in acidic medium n colourless in basic mediums.(used to check end point of neutralisation titrations)
oxidation:usually using KMnO4. if solution undergoes oxidation, it will decolourise purple KMnO4. K2Cr2O7 is used sometimes as well. also decolourises when solution gets oxidised. -
these kinds of things must memorise wan, u must noe the rxns n products plus their colours at the back of ur hands(or brains)... tt's wat chemistry is abt... good luck
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where?My txtbk only hav ammonia and sodium hydroxideOriginally posted by khk:these kinds of things must memorise wan, u must noe the rxns n products plus their colours at the back of ur hands(or brains)... tt's wat chemistry is abt... good luck -
some i can know...but other things like
barium etc i dunno sia.
i tot the most basic is like
Iron 2, Iron 3 and Copper 2
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At A Levels, u will learn about Ligand exchange, colour complex and all those stuff. Then you will truely know how the colour come abou, its from the spectrachemical series. Somethin like d-d transition metals absorb certain wavelength and some stuff.
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Is there a table online or sth where i can refer to?Cant seem 2 find it
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Got. SEAB website chem syllabus got.Originally posted by lpx88:Is there a table online or sth where i can refer to?Cant seem 2 find it
If you memorize the test result, it'll give you more time. However if you don't want to memorize, there is table provided.