Special Posting: Practical Chemistry a.k.a. P3

Oke tinggal sehari atau dua hari lagi buat practical. Menurut gw, nih paper yg paling sulit, soalnya kesalahan dikit aja bisa bikin resultnya ngaco dan amburadul. Such small stupid mistakes can be irrelevant and sometimes unnoticeable. Example, using the same dropper for different unknown substances. Klo misalnya precipitatenya warnany bisa kuning atau merah atau ungu atau putih, I say it is still safe to combine them. Tp klo ada 3 unknown substance, trus ada 2 yg precipitare warnanya putih, good luck.

Usually they will provide two droppers, I suggest you use one for to add the acids and bases (you know, you will need to use droppers to add ammonium hydroxide or HCl) and use the other one to add the unknown substance to empty test tube. Terus siapin satu beaker kosong isinya distilled water buat bersihin droppernya. Jadi abis pake buat satu reagent lu pake droppernya buat ambil air trus buang lah airnya kemana. Minimal bisa buat reduce contamination.

Trus buat calculation. Inget biarpun titrasi lu ngaco, calculation nggk ada accuracy marknya. Jadi, sebisa mungkin, try to get full mark in calculation part. 5 marks mungkin kecil, tapi bisa nyelamatin kita. Klo perlu hapalin semua calculationnya biar lebih confident. Confidence is the key to succeed in this exam. Also in qualitative analysis, sometimes you can actually guess which substance is which even if you haven't finished the whole set of questions. You can actually save time here by writing the possible outcome before we actually test it. Jadi biarpun salah waktu kita coba, tp nulis observasinya bener, kita masih dapet mark.

Klo lu orang lebih confident, boleh juga coba kerjain qualitative nya dahulu. Jawaban di qualitaive lebih exact. Pengecualian kalau titrasinya menggunakan oxidising agent (KMnO4 dan yg lainnya). Klo kelamaan ditinggalin, nanti reagentnya bisa keoxidize duluan, resulting in inaccurate measurement.

Trus klo ada yang ambidextrous atau at least bisa kerja pake 2 tangan, gunakanlah dua tangan anda. Tp klo misalnya lu orang begitu pake 2 tangan langsung tangan kanannya stop bekerja, jangan dicoba.

Klo ada dilution (yg musti dimasukin ke dalam tube aneh terus dikocok), lu orang buka distilled water tubenya, terus tumpahin, terus klo udah level tertentu, baru pake tube kecilnya. Dan klo udah approaching the line, ganti pake dropper biar meniscus readingnya pas di line. Beda sedikit aja bisa deviate the result by a lot. Trus pas di shake, ati2 jgn sampe ada yg tumpah airnya (sedikit gpp), reason same as above.

Jangan lupa tabulate all of the results, even though if you are not asked to. Gw pernah ilang 2 mark gara2 nggk nulis table di bagian awal2. Jangan panik waktu ngerjain, kejadian dulu ada anak ngambil A-level, saking groginya sampe mecahin apparatusnya (nggk tau apparatusnya apa). Trus semua data harus 2 decimal places, klo nggk bisa ilang tuh 1 mark.

Klo bisa, hapalin semua perubahan warna saat titrasi. Klo misalnya diminta titrasi sampe warna pink pake methyl orange, harus bener2 exact warna itu. Always use white tile to let us differentiate the colour better. Klo bener2 kepepet (definisi kepepet: udah coba 3 kali tapi bedanya sampe 5 cm3 atau warnanya lu bener2 nggk tau) (*warning* very risky), cb ngintip temen2 yg lain atau invigilator punya practical. Glancenya of course jgn ketauan, main mata dikit aja. Sebaiknya klo bingung tanya dulu, klo nggk dihiraukan baru.... (anak baek jangan menyontek. Inget ini bener2 risky. Klo ketahuan bisa automatic failure, so jangan main api klo nggk mau kebakar). Trus klo misalnya Ms. Ine liatin lu orang punya practical, try to just ignore her face and body language and expression.

Klo kerjain, tolong-tolong dengan sangat jangan pernah buru-buru kaya dikejar setan atau mau show off. With proper time planning and by realizing your ability, you should be able to allocate your time wisely and judgmentally. No need to rush with reason such as "later I don't have time to do the written work". Plan, plan, plan!

Jangan cheat your result, bcos most probably the examiner will notice. (I don't now actually how to cheat here though)

Trus klo ada pertanyaan yg regarding improve the quality of experiment atau why such experiment is blablabla, jgn panik. The best answer is always the simplest answer but we should not simplify our point. Pikir pake kepala dingin, klo mereka mintany simple modification, jgn pikir yg aneh aneh. Conduct experiment in vacuum is one of the most desperate answer. Liat sekitar lu dan liat apparatus2nya, trus pikir lagi. Klo nggk bisa lompatin aja daripada ngabisin waktu.

Last but not least doa. Biarpun udah disiapin seperfect mungkin, tapi selalu ada uncertainty. By conducting our experiment accurately and precisely, we should reduce those uncertainty by a great amount. But still, it is always good to have faith.