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ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
--- Quote from: Kirin on December 09, 2010, 07:08:09 am ---http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_w04_qp_1.pdf
Question 13. I understand the answer is D and that you need a strong acid and base, but why ? What is the chemistry behind all of this ?
Why wouldnt a strong acid and weak base give a SHARP colour change ?
What chapter does this appear in the chem book by Brian Ratcliff ?
--- End quote ---
A strong acid and a strong alkali gives the sharpest end-points. Weak bases or acids take more time to dissociate and hence the end-point is not as sharp as that using strong solutions.
It appears in the chapter Equilibria ---> The part in A2 where you deal with indicators.
elemis:
http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_w05_qp_1.pdf
Question 3
I know the answer is B... I actually got this question correct. However, I want to check if my reasoning is correct and that I didnt get this by some fluke.
Once the p electron in option B is removed a fully filled s orbital is left. This orbital has a stable arrangement of electrons because it is filled and hence requires a larger IE to remove these electrons.
Is this correct ?
The Golden Girl =D:
--- Quote from: Kirin on December 10, 2010, 01:00:41 pm ---http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_w05_qp_1.pdf
Question 3
I know the answer is B... I actually got this question correct. However, I want to check if my reasoning is correct and that I didnt get this by some fluke.
Once the p electron in option B is removed a fully filled s orbital is left. This orbital has a stable arrangement of electrons because it is filled and hence requires a larger IE to remove these electrons.
Is this correct ?
--- End quote ---
Yes , I chose B too because the Element is in Group 1 , ur explanation ,hence the Highest I.E. among the other =]
Master_Key:
--- Quote from: ~ Amatu Allah ~ Aka GG on December 10, 2010, 01:11:29 pm ---Yes , I chose B too because the Element is in Group 1 , ur explanation ,hence the Highest I.E. among the other =]
--- End quote ---
To remove the first electron is easy as it is the only electron, but next shell is full, sheilding effect is higher and thus requires higher energy.
elemis:
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?
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