O level pratical chemistry question.

• mrcoconut

  13 Oct 07, 13:47

  XCO3 and YCO3 are both carbonates of the same group.
  
  using items found in the school labatory. determine which of the element X or Y have a higher Ar.
  
  my solution, i dontknow if its correct.
  
  - 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.
  
  can someone check if its correct?
  
  thanks!
• mrcoconut

  13 Oct 07, 17:57

  no one know how to do?
• lpx88

  13 Oct 07, 17:59

  I bullshitted that one
• Darkness_hacker99

  13 Oct 07, 20:56

  If I were to do this..
  
  I'll just find out what are the Cations of the two compound. Then compare lor.
• mrcoconut

  13 Oct 07, 20:59

  Originally posted by Darkness_hacker99:

  If I were to do this..
  
  I'll just find out what are the Cations of the two compound. Then compare lor.

  huh? nono must explain in the acid bases and salt way.
  
  but mind to explain your method? must write step by step
• ^tamago^

  13 Oct 07, 21:02

  ur solution is what they are looking for, but if i can test cation i'll also test cation.
• Darkness_hacker99

  13 Oct 07, 21:03

  Originally posted by ^tamago^:

  ur solution is what they are looking for, but if i can test cation i'll also test cation.

  Yar.
• mrcoconut

  13 Oct 07, 21:05

  Originally posted by Darkness_hacker99:

  Yar.

  rlly correct ah?! YAYYYYY
  
• eagle

  14 Oct 07, 08:38

  eagle's sister here
  i wrote the same answers as u!
  but some of my friends wrote with a known mass, add a known mass of acid and let the co2 escape
  then record the mass left
  use the original mass minus the lost mass
  then find mols etc
  but is around the same i think
  haha
• Hello Kitty

  14 Oct 07, 08:46

  paiseh.
  
  all returned to teecher le.
• lpx88

  14 Oct 07, 08:51

  Originally posted by eagle:

  eagle's sister here
  i wrote the same answers as u!
  but some of my friends wrote with a known mass, add a known mass of acid and let the co2 escape
  then record the mass left
  use the original mass minus the lost mass
  then find mols etc
  but is around the same i think
  haha

  Ok....
• Darkness_hacker99

  14 Oct 07, 17:50

  Originally posted by eagle:

  eagle's sister here
  i wrote the same answers as u!
  but some of my friends wrote with a known mass, add a known mass of acid and let the co2 escape
  then record the mass left
  use the original mass minus the lost mass
  then find mols etc
  but is around the same i think
  haha

  Hi.
• lpx88

  14 Oct 07, 18:51

  My chemistry was always on the wrong side of the passing marks...so i wrote some farked up crap about titration and such..can get 1-2 marks i happy liao
• tanjun

  14 Oct 07, 23:03

  Originally posted by mrcoconut:

  XCO3 and YCO3 are both carbonates of the same group.
  
  using items found in the school labatory. determine which of the element X or Y have a higher Ar.
  
  my solution, i dontknow if its correct.
  
  - 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.
  
  can someone check if its correct?
  
  thanks!

  On the whole, it is ok and correct. In my opinion, actually, you can add in excess dilute HCL into XCO3 or YCO3 so that it ensures that the reaction is complete.
• wonderamazement

  14 Oct 07, 23:34

  Got say "excess"?
• Darkness_hacker99

  14 Oct 07, 23:41

  Originally posted by wonderamazement:

  CMY are you seeing this?

  Who is CMY?
• tanjun

  15 Oct 07, 00:34

  Originally posted by wonderamazement:

  Got say "excess"?

  Excess means that one can ignore the measurements in terms of mass of HCL cos in my opinion, it doesn't matter since you have added "excess". But it is ok to measure the mass of HCL at the start just that the mass of HCL can be anything equal or above the mass of the carbonate.
• airgrinder

  15 Oct 07, 00:42

  wah!!!! o lvl chem so chim nowadays...
  
  i only know sugar + H2o + coffee bean sulphate = kopi
  
  
• lpx88

  15 Oct 07, 10:23

  Originally posted by airgrinder:

  wah!!!! o lvl chem so chim nowadays...
  
  i only know sugar + H2o + coffee bean sulphate = kopi
  
  

  Wtf...
• absol

  16 Oct 07, 16:33

  quote ts "using items found in the school labatory. determine which of the element X or Y have a higher Ar. "
  
  they nv say determine ar value...so i wrote add excess hcl to same weight of xco3 and yco3 ( so that gas produced is determined by e carbonates), den see which 1 produce lesser gas, and thats the 1 with the higher ar.
  
  cos no. of moles = mass/mr
  
  ur mass constant for both gases, vol of gas produced is due to no. of moles, so the bigger e mr, the smaller the no. of moles and so the carbonate with e bigger mr will produce lesser gas....