TYS 'O' LVL chem questions

• eagle

  20 Oct 08, 10:21

  d) calcium carbonate is insoluble in water.name two sustance that, when mixed in solution will form a precipitate of calcium carbonate?

  I not very sure. Forgot a lot of chem

  I guess his answer of calcium chloride and sodium carbonate should be correct

  you have to take 2 salts that are soluble in water to mix together

• gunner77

  20 Oct 08, 10:23

  oops not this question

  i mean the relative molecular mass question. sorry.

   

• eagle

  20 Oct 08, 10:26

  His answer

  3a) relative molecular mass of a compound is the average mass of one molecule of the substance compared to 1/12 the mass of carbon-12 atom

  This is because Carbon-12 atom has it's molecular mass at 12. It is sort of used as the standard measurement.

  1/12 of the molecular mass of the carbon-12 atom means molecular mass of 1.

  Relative molecular mass, the key word is in the 'relative'. So saying that it is relative to 1/12 of carbon atom; carbon-12 atom is the reference mass.

• gunner77

  20 Oct 08, 10:28

  ok i tink i roughly get it. thanks alot guys !

• eagle

  20 Oct 08, 10:31

  gd luck

  dun waste my effort of doing undelete in my brain for some chemistry knowledge

• gunner77

  20 Oct 08, 10:33

  just hope tat watever the TYS has

  will come out

  *basic oxide and amptheoric oxide react with acid to form salt and water

  * only amptheoric oxide react with alkaline to form salt and water

  ok i must rmb this two points.

• maurizio13

  20 Oct 08, 10:33

  Originally posted by MyPillowTalks:

  230pm

  im scared

   

  fasterly go middle road guan yin temple pray.

   

   

• UltimaOnline

  20 Oct 08, 10:53

  LAST MINUTE 'O' LEVEL QN!!!

   

  In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

   

  Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

• Ah sian

  20 Oct 08, 10:56

  nh3 = 4 atom

  nitrogen = 2.8.4

  h3 = 3 molecue

  3 reacting 1 not reacting isit

• wishboy

  20 Oct 08, 10:59

  Originally posted by UltimaOnline:

  LAST MINUTE 'O' LEVEL QN!!!

   

  In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

   

  Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

  6 electrons involved, 2 not involved.

• Ah sian

  20 Oct 08, 10:59

  how u get

• wishboy

  20 Oct 08, 11:02

  

• Ah sian

  20 Oct 08, 11:03

  shit i thought electron is nucleon

  die liao

• davidche

  20 Oct 08, 11:04

  Originally posted by UltimaOnline:

  LAST MINUTE 'O' LEVEL QN!!!

   

  In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

   

  Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

  how many valence electrons you mean?

• davidche

  20 Oct 08, 11:05

  Originally posted by Ah sian:

  shit i thought electron is nucleon

  die liao

  I can spot another mistake. And you tot nucleon is neutron?

• gunner77

  20 Oct 08, 11:07

  5 years of secondary education

  it just boils down to the 1h15min

  

• Ah sian

  20 Oct 08, 11:08

  Originally posted by davidche:

  I can spot another mistake. And you tot nucleon is neutron?

  what u mean nucleon is neutron

  where u spot from my post

  i thought nucleon is aka  mass

  neutron is nucleon - proton

• Ah sian

  20 Oct 08, 11:09

  i very scare leh

• Ah sian

  20 Oct 08, 11:10

  i really very scare leh

• gunner77

  20 Oct 08, 11:11

  relax relax.

  just do ur paper, mind ur own business.

  don look left right centre, just focus.

• MyPillowTalks

  20 Oct 08, 11:14

  ssccareredd

  i duno anything

  hhheeellp

   

• UltimaOnline

  20 Oct 08, 11:16

  No, the qn didn't say "valence", the qn asked
  "how many electrons in 1 molecule". So nobody got the correct ans.

   

  Solution

   

  3 bonds = 6 electrons involved in bonding

   

  2 valence electrons not involved in bonding + 2 inner shell electrons not involved in bonding = 4 electrons not involved in bonding.

• Ah sian

  20 Oct 08, 11:21

  ya what wishboy get it right

  i think he forgot to add the inner electron

• Ah sian

  20 Oct 08, 11:34

  how you know what is a redox reaction

  how u determine the oxidation state

  and what is a precipation

• Ah sian

  20 Oct 08, 11:38

  uppppppppppp