how was combined chem?

• Sgforum King

  2 Nov 09, 16:04

  1 word
  
  Fail

• bratorbread

  2 Nov 09, 16:20

  question 9b how to conduct experiment to find the speed of reaction sia .

  i wrote

  add excess hcl to mg until all mg react

  calculate time taken

  calculate vol. of hydrogen gas produced.

  plot a graph of vol. of hygroden gas produced against time taken.

  calculate gradient , = speed of reaction .

   

  i know its wrong but will i get any marks . like 2 or 3 lol.

• Sgforum King

  2 Nov 09, 16:21

  i fuck care my com science liao ar

• Music-Life

  2 Nov 09, 16:38

  So bad meh? Paper relatively easy wad. No real questions that stump ppl. Only careless, i go put iron (II) Sulphate as Fe(SO4)2. Even section B all the questions also rather give away if you know how to answer.

• Sgforum King

  2 Nov 09, 16:40

  GG lucky i got DPA

• yiha093

  2 Nov 09, 16:45

  even dpa need like 25 or sth =.=

   

• Sgforum King

  2 Nov 09, 16:46

  Originally posted by yiha093:

  even dpa need like 25 or sth =.=

   

  26

• Froztspectre

  2 Nov 09, 17:00

  Either B or A.

   

  I dropped from Pure Chem to Combine Chem around October.

  At first still quite scared,

  after doing the paper, i was shocked. It was quite easy in my opinion.

   

  To find Speed of Reaction, just calculate the amount of gas produced/min. Add magnesium into Conical flask, use rubber bung to pass gas produced into calibrated Gas Syringe. Measure amount of gas produced at 1min,2min,3mind,... to 5 mins.

  Previously in Pure Chem do before designing experiment, so i'm already prepared for this question. So relatively easy for me.

   

  The only questions i sucked at = Q(A), Mole and the next stupid Alpha, Beta, Gamma shit...

   

  The rest all quite simple for me.

• Xuihui

  2 Nov 09, 17:04

  some answers clarified by teachers..

  For the qns where we've to match the diagram (in letters) with question given  :

  E

  D

  C

  B

  A

   

  Qns which regard to reactivity series withe the table given

  aphla ...hyrogen ..,,..

  The answer for the 2nd and last qns  is alpha and e...(the last element in the table)

   

  Qns with table/diagram given (Ph value qns)...

  the ion of the left side is H+ and the right is OH-

  the product formed will be  sodium sulfate .

   

   

  The paper was quite easy.. think they will moderate the marks  :)

• Froztspectre

  2 Nov 09, 17:14

  O good, means my alpha beta thingy not as badly done.

  Means i only screwed up at mole and Q(A).

• Daisuke-kun

  2 Nov 09, 17:22

  i had careless mistakes. fuck.

  time for physics though.

• xBer

  2 Nov 09, 19:36

   

  paper pretty easy luh. haha can score full marks?  XD cause didn't have any careless mistakes.

  what i did for the question on rate of reaction was to draw out the diagramn
  gas syring , flask etc.

  i believe drawing is much easier to summarise the experiment, but of course dun leave out the steps.

  the codeword question stunned me when i first read it. overall, was a easy paper. though i dun think there will be a drastic moderation like what emaths would be like.

  good luck to the rest of you guys take humanities tmr.

   

• JaSoNhSu92

  2 Nov 09, 20:05

  Originally posted by Xuihui:

  some answers clarified by teachers..

  For the qns where we've to match the diagram (in letters) with question given  :

  E

  D

  C

  B

  A

  
  sequence reversed