Qualification > Sciences
ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
--- Quote from: Ari Ben Canaan on December 21, 2010, 08:07:15 am ---When the yellow liquid NCl3 is stirred into aqueous sodium hydroxide, the reaction that occurs
can be represented by the following equation.
2NCl3(l) + 6NaOH(aq) ---> N2(g) + 3NaCl (aq) + 3NaOCl (aq) + 3H2O(l)
What will be the result of this reaction?
1 The nitrogen is oxidised.
2 A bleaching solution remains after the reaction.
3 The final solution gives a precipitate with acidified silver nitrate.
The MS says 2 and 3 are correct only.
Why isnt 1 also correct ? It is obvious that Nitrogen goes from an oxidation state of -3 in NCl3 to 0 in N2. Hasnt the Nitrogen been oxidised?
--- End quote ---
Dude the oxidation number of nitrogen in NCl3 is +3 and not -3. Therefore it gets converted to 0 which means it is reduced. ;)
elemis:
http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s10_qp_11.pdf
I must be really daft.... but I cant figure out why the answer is as stated in the MS.
Question 1
elemis:
--- Quote from: Martin Luther King Jr on December 21, 2010, 11:15:16 am ---Dude the oxidation number of nitrogen in NCl3 is +3 and not -3. Therefore it gets converted to 0 which means it is reduced. ;)
--- End quote ---
Damn, right. Can you answer my other question ?
Deadly_king:
--- Quote from: Ari Ben Canaan on December 21, 2010, 11:15:45 am ---http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s10_qp_11.pdf
I must be really daft.... but I cant figure out why the answer is as stated in the MS.
Question 1
--- End quote ---
1.What could be the proton number of an element that has three unpaired electrons in each of its
atoms?
A 5
B 13
C 15
D 21
You just have to write the electronic configuration of the elements.
5 -----> 1s22s22p1 : Only one unpaired electron.
13 -----> 1s22s22p63s23p1 : Only one unpaired electron at all.
15 ------> 1s22s22p63s23p3 : 3 unpaired electrons only.
21 ------> 1s22s22p63s23p64s23d1 : Only one unpaired electrons.
So answer is C. ;)
Is it right?
elemis:
I got answer C too.... I think I was looking at the wrong MS at the time -_-
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