gd rucks for ppl taking practicals in the near future~

• lpx88

  11 Oct 07, 18:29

  Originally posted by fstein:

  all should be constant
  
  but my sch use methyl and yours is screened. meh.

  It's a huge mistake to use screened methyl
  
  Huge range of colours = Huge range of answers
• kct360

  11 Oct 07, 18:37

  Originally posted by fstein:

  20mins is too long
  
  the gas all liberated within the first minute

  nth liberated. no gas was evolved throughout the 20mins. the solid didnt change colour or anything as well.
• lpx88

  11 Oct 07, 18:40

  Originally posted by kct360:

  nth liberated. no gas was evolved throughout the 20mins. the solid didnt change colour or anything as well.

  Quite a num of my friends kena too
  
  I test test test nothing come out
  
  Then my friends were saying that too little solid R put in liao... they put the whole portion then can pick up the little oxygen
  
  My tcher say should be..heat to black..then silver..then melt into orange
  
  
• masterofIT

  11 Oct 07, 19:33

  Then the planning quest?
  
  how u guys do it?
  
  i mentioned abt thermal decompostion of both XCO3 and YCO3 with CO2 formed. Then after reaction[effervescence]. Calculate the Ar then compare..LOL
• mrcoconut

  11 Oct 07, 19:44

  Originally posted by masterofIT:

  Then the planning quest?
  
  how u guys do it?
  
  i mentioned abt thermal decompostion of both XCO3 and YCO3 with CO2 formed. Then after reaction[effervescence]. Calculate the Ar then compare..LOL

  - react recorded and identical masses of HCl with same masses of X and Y
  
  - record starting mass.
  
  - collect and record amount of CO2 gas produced using a gas syringe.
  
  - after awhile, record mass and volume again
  
  - using formula, mass/volume = mols to find concentration in mols
  
  - using formula mass/Mr = mols, to find Mr of both X and Y
  
  - repeat experiment to obtain a more accurate result.
  
  this was what i did. dontknow correct anot
• lolhahalol

  13 Oct 07, 15:14

  Originally posted by lpx88:

  It's a huge mistake to use screened methyl
  
  Huge range of colours = Huge range of answers

  screened methyl would be more accurate
  theres a more obvious change in colour unlike methyl which is red and orange which is quite similar.
  
  for titration
  i guess the reason why some of you got 20+ for the NaOH is because u used a 20cm3 pipette whereas others use 25cm3 pipette
• lolhahalol

  13 Oct 07, 15:19

  the summary for qa should be
  Lead [ not lead(II) as they asked for the element not ion ]
  Oxygen
  NO3-
• limywv

  13 Oct 07, 22:55

   

   

   

   

  
  
• lpx88

  14 Oct 07, 08:58

  Bio prac ftw!!!
  
  Die liao..drawings
• kct360

  16 Oct 07, 14:59

  rwar. bio prac sucks. so many drawings!!!
• lpx88

  16 Oct 07, 16:26

  Originally posted by kct360:

  rwar. bio prac sucks. so many drawings!!!

  Smore supposed to be T.S for W2 i go take L.S...ZZZZ....Bio prac sucks..
• kct360

  16 Oct 07, 16:36

  heng my school prelim got do. this part exactly the same.