How to do well in tests/exams?

Audi SG

Right, so I've just had a chemistry test. Truth be told, I prepared for this over the length of a few days. I did memorize the necessary stuff (Reactions, etc) and I did relevant questions for extra practice. Also, I went through past tutorial questions which I thought were interesting.

Much as I expected to do well for it, I ended up screwing the paper. Largely because there was this particular question whcih requires us to specify the synthesis of an organic compound into another. I tried to go through the reactions in my head but just simply could not come up with an answer (which is needed to resolve the remaining parts of the question)

So yeah... obviously, I wasn't in the mood to read through the last few questions because I was mulling over that question, which carries plenty of marks.

This has happened to me a few times over the past 3 years... sometimes I studied all that I felt were necessary, practised all that there is, but still ended up not doing well. Also, sometimes, those tests can be easy to manage (and I know it as well) but I just can't come up with an answer within such a short time frame...

Is there any way I can try to resolve this issue? I just can't help thinking about it.

Sorry for raising an issue whcih some may think is trivial... but yeah. Thanks for reading.

Summer hill SG

I want to ask you

Audi SG

I want to ask you

Of course, lol. If not, I would have only read my notes instead of finding time to do extra reading up and practise questions.

I have made condensed notes which help me recollect the materials in 5-10minutes.

So here are the answers for your questions.

1. All the tutors know I pay attention in class (most have told the entire class about that, lol)

2. I always complete my homework on time. I never missed doing a tutorial before class.

3. Yes I stayed back in school 2-3 times a week till 8pm just to self-study.

Yami king2005 SG

I think the solution during exam is to do the question which you know the answer. Those question which you are uncertain whether you can secure the marks, you can skip first and do later. This way, you would at least know how to do the question which you know how to do. I do this all the time.

UltimaOnline SG

Post that particular synthesis question.

Audi SG

Post that particular synthesis question.

Convert...

CH3CH2CH2Br to CH3CH(CH3)COOH.

There should be 3 steps between the reactant and the product.

DIdn't occur to me that I should have started with elimination of halogenoalkane. And I totally didn't want to give up on such a supposedly simple question.

Summer hill SG

Maybe you are very careless in your work?

Audi SG

Maybe you are very careless in your work?

True, but not that careless all the time lol! I think my problems in science subjects rarely have to do with carelessness.

Thanks for the suggestion anyways lol :)

UltimaOnline SG

Convert...

CH3CH2CH2Br to CH3CH(CH3)COOH.

There should be 3 steps between the reactant and the product.

DIdn't occur to me that I should have started with elimination of halogenoalkane. And I totally didn't want to give up on such a supposedly simple question.

Thought process :

CH3CH2CH2Br to CH3CH(CH3)COOH.

Since the final product is branched, a simple nucleophilic substitution will not suffice.

Elimination of HX following by addition of HX, is useful for converting terminal alkyl halides to internal alkyl halides.

Notice that the product has one more C atom than the reactant (which means we need a C nucleophile, such as the cyanide nucleophile, or a Grignard reagent, or a Wittig reagent).

Hence, substitute away the halogen (good leaving group) with CN by heating under reflux with NaCN(alc).

Carry out acidic hydrolysis of CN to convert it into (an amide intermediate which is further hydrolyzed to) COOH.

SBS n SMRT SG

This is an interesting question indeed ... keep on thinking on nucleophilic addition

SBS n SMRT SG

btw, TS mentions 3 steps, utima your method is technically 4 steps

Step 1: Alc KOH, refulx

Step 2: HX, rtp

Step 3: Alc KCN, reflux

Step 4: H+/H2O heat

UltimaOnline SG

btw, TS mentions 3 steps, utima your method is technically 4 steps

Step 1: Alc KOH, refulx

Step 2: HX, rtp

Step 3: Alc KCN, reflux

Step 4: H+/H2O heat

There is a way to cut out step 2, but H2 Chem JC students aren't familiar with this process.

Step 1 (Elimination of HX) : KOH (alc), heat under reflux

Step 2 (Hydrocyanation) : HCN (alc), Ni/Cu/Pd catalyst, heat under reflux

Step 3 (Acid-catalyzed Hydrolysis) : H+/H2O, heat under reflux