Combined Chemistry Qns

• ceecookie

  6 Oct 07, 16:41

  
  
  
  
  Can anyone explain the respective answers for this question?None of my notes explain the answers.
  
  
  
  3b) Why is the correct answer E? AFAIK proton number is the same as the electrons' so it should be B since it got 5 electrons.
• eagle

  6 Oct 07, 16:47

  heh me return chemistry to teacher liao
• ^tamago^

  6 Oct 07, 16:58

  A = Beryllium
  B = Nitrogen
  C = Flourine
  D = Oxygen
  E = Boron
  
  A is metal. The rest are non-metals.
  
  (b) E. A lone Boron atom indeed has 5 protons and 5 electrons.
  (c) D. O2
  (d) A and C. A as reducing agent, C as oxidising agent.
• ceecookie

  6 Oct 07, 17:02

  Originally posted by ^tamago^:
  
  (b) E. A lone Boron atom indeed has 5 protons and 5 electrons.
  

  But the Boron as shown is not lone isit?Why does it show only 3 electrons?
• ^tamago^

  6 Oct 07, 17:04

  Originally posted by ceecookie:

  But the Boron as shown is not lone isit?Why does it show only 3 electrons?

  outer shell, outer shell.........
• ceecookie

  6 Oct 07, 17:07

  Originally posted by ^tamago^:

  outer shell, outer shell.........

  Oh i get it.
  As in total,not in the outer shell alone.
  
  2.3 = 5
  
  2.5 = 8.
• ^tamago^

  6 Oct 07, 17:09

  yeah lor.
  
  B = 1s²2s²2p¹ = 2+3.
• HyuugaNeji

  6 Oct 07, 17:14

  fe2+ solution is green lo...most solution with fe2+ will be green...what to do...god dictate it to be green. light spectromecy due to energy levels of electrons cause something to be of a different color.
  
  What a chemistry student can do is guess lor. So can guess from 1 out of 100+ elements right? There are only 100+ elements in this world. Master all the elements and how they combine with one another and you will be god.
• Darkness_hacker99

  6 Oct 07, 17:15

  Originally posted by ^tamago^:

  yeah lor.
  
  B = 1s²2s²2p¹ = 2+3.

  Atomic orbital is not under O level syllabus.
• Darkness_hacker99

  6 Oct 07, 17:18

  To know what's metal R, you must know the answer for green ppt U.
  
  Metal R + Sulphuric acid = R sulphate + Hydrogen
  
  R sulphate + Sodium Hydroxide = R hydroxide + Sodium Sulphate
  
  If green ppt is obtain, it's Iron(II) hydroxide.
  If red/brown ppt is obtain, it's Iron(III) hydroxide.
  
  From this Sodium hydroxide test, we can tell the the Cation ion is Fe2+
  Therefore the Metal R is Iron.
  
  First you must know that the use of acidified Barium chloride is to test for presence of the of sulphate ions. If sulphate ions is present, then white ppt will be obtain.
  
  Background information that you might need to know.
  
  Chlorine is an oxidizing agent. Which mean, it'll cause something to oxidized. So in this case, Fe2+ is oxidized to Fe3+
  
  The brown solution after bubbling is Iron(III) sulphate.
  
• HyuugaNeji

  6 Oct 07, 17:21

  Here's a question for chemists:
  
  1) Why is oxygen gas colourless? (Dont tell me because you cant see it)
  
  Here's a question for biologists:
  
  1) Why is glucose sweet? (Dont tell me it contains sugar or crap cos why is that crap sweet?)
  
  
• ^tamago^

  6 Oct 07, 17:22

  Originally posted by Darkness_hacker99:

  Atomic orbital is not under O level syllabus.

  extra info.
• Darkness_hacker99

  6 Oct 07, 17:23

  Originally posted by ^tamago^:

  extra info.

  
• ^tamago^

  6 Oct 07, 17:26

  Originally posted by Darkness_hacker99:

  

  
• Darkness_hacker99

  6 Oct 07, 17:34

  Originally posted by HyuugaNeji:

  Here's a question for chemists:
  
  1) Why is oxygen gas colourless? (Dont tell me because you cant see it)
  
  Here's a question for biologists:
  
  1) Why is glucose sweet? (Dont tell me it contains sugar or crap cos why is that crap sweet?)
  
  

  Why is glucose sweet?
  
  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html#sweet
  
  I hope this page can help you.
• HyuugaNeji

  6 Oct 07, 17:47

  Originally posted by Darkness_hacker99:

  Why is glucose sweet?
  
  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html#sweet
  
  I hope this page can help you.

  thanks. that's a good site.
  
  A chem prof told me that they are still working on why some stuff like sucrose, glucose and fruitose are sweet. They guess it has to do with the structure of the chemicals and their bondings.
  
  And this brings me to the next question: Why is Sodium saccharin so much sweeter than the rest?
  
  Pls refer to: http://en.wikipedia.org/wiki/Sweet who dare to drink sodium saccharin product?
• Darkness_hacker99

  6 Oct 07, 17:58

  Originally posted by HyuugaNeji:

  thanks. that's a good site.
  
  A chem prof told me that they are still working on why some stuff like sucrose, glucose and fruitose are sweet. They guess it has to do with the structure of the chemicals and their bondings.
  
  And this brings me to the next question: Why is Sodium saccharin so much sweeter than the rest?
  
  Pls refer to: http://en.wikipedia.org/wiki/Sweet who dare to drink sodium saccharin product?

  Yar. Structures and bonding does plays a huge part. But we must not overlook the Biological part of the research. Because to understand and solve the mysteries of this complicated and complex problems, it definitely will require people from different specialization.
  
  Does your prof's team have biologist and neurologist?
• HyuugaNeji

  6 Oct 07, 18:02

  Originally posted by Darkness_hacker99:

  Yar. Structures and bonding does plays a huge part. But we must not overlook the Biological part of the research. Because to understand and solve the mysteries of this complicated and complex problems, it definitely will require people from different specialization.
  
  Does your prof's team have biologist and neurologist?

  No. I am not a chemistry nor biology nor life science student. I just ask this question to the chem prof (GEM module) for fun. Cos i pay school fees mah.