SPAz Again!

Hi pple! ready to go SPAz?

Somethings i wanna highlight so you dun go spaz during SPA. (haha i'm so punny)


1.When creating ur mtd make sure that for the test u choose you are careful to predict the correct outcomes.

2. Make sure the procedure you write is IN STEP with your method! some students propose a mtd like say use 2,4 DNPH first then use Na2CO3, but in their procedure its some other order!!

3. THEORY and RELIABILITY: again pls, be specific for the question. like for eg when describing the theory abt silver halide test for R-X, since we are using chloroethane, you should adapt the theory for that compound. So you'd write that OH- hydrolyzes chloroethane, to liberate Cl- ion. Dont bother to write general things like RX and X- ion.

What I mean is, answer the question!!!

4. LIMITATIONS. many students are not good at this. they tend to copy wholesale from notes.
i)Please answer in proper qn context. Like for eg 24DNPH test for aldehyde, the notes limitations says that it can give +ve for ketones too... now, whats the point of writing that if there arent any ketones ard anyway?? in this context, 24 DNPH gives an unambiguous +ve

ii) note that hydrolysis requires strong heat, while acid base neutralisation does not ( for amides vs ammonium salts for eg)



5. SPELL the name of the reagents. 2,4 dinitrophenylhydrazine

6. CONDITIONS!! be specific. like especially (aq), state symbols, and warming.

7. when giving procedure, be specific about the + and - observations!!
so again dont give general statements like.. observe for gas that turn red limus blue.

You should write:
add 2 cm3 dil NaOH(aq) to 1 cm3 of sample and heat strongly for 5 mins in boiling water bath.
Test for gas evolved using moist red litmus paper.
N-methyl propanamide will evolve gas turning moist red litmus blue, while compunds x y and z will not.

Notice If you have to test for gas, you shd describe how you are going to do it, as in "test for gas using..."

You should also specifiy the observations (both +ve or - ve) for the compounds being tested on.

8. Remember to DISSOLVE SOLIDS.

9. Remember to specify, "to fresh samples of cpds..." when describing procedure

10. for safety concerns, write both the measures taken and WHY these measure are taken. eg, do expt in fume cupboard to prevent toxic fumes from escaping to environment.

ok break for now