Mock for CE guys 2 (ans)

Puppet

麻煩把問題拿出來討論
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1 DDCDC
6 CBDDD
11 BADCD
16 DBBCC
21 A
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[ 本帖最後由 Puppet 於 27-4-2008 12:17 編輯 ]

Puppet

原帖由 piyopiyo 於 26-4-2008 13:27 發表
咪話,AL都考完等 UE oral ja ma[[tk_35]]

puppet 兄這份好似好難...

係, 因為目的唔係出份似paper 2的野
只係想throw些unfamiliar situations/conceptual 野

Puppet

1. (3) × Too close b.p.

2.
A. ×
Volume increases => [H+(aq)] (molarity) decreases => pH = - log [H+(aq)], pH increases
Note that the solution is still neutral (assume ethanol is not an acid)
D.
Neutral iff [H+(aq)] = [OH-(aq)]
At higher temperatures, in pure water [H+(aq)] = [OH-(aq)] > 10^-7
pH < 7 but the solution is of course neutral

10.
General rule: Free elements as either reactant or products => must be redox (except C(graphite) -> C(diamond))
By conventional methond, C + 12(+1) + 6(-2) = 0 => C = 0
In fact, referring to the structure of glucose (as an example),
O.N. of 4 of the C atoms in C6H12O6 = 0
O.N. of C in aldo group of C6H12O6 = -1
ON. of the other terminal C of C6H12O6 = +1
So, please follow the general rule.

14. should be C
I typed it wrongly

[ 本帖最後由 Puppet 於 27-4-2008 12:25 編輯 ]

Puppet

原帖由 777kong 於 28-4-2008 14:17 發表
would u mind explain question 1 and 7?

#1 don't understand

#7 how can i know that it is a simple structure?

1.
Normal water contains all isotopes of H and O.
Of course it is a pure substance of the same thing.

Self-ionization of water H2O <---> H+ + OH-
There is D+ and 1H+ in water
There is D-O-1H in water
1H-D can be formed as hydrogen gas

7.
佢唔係無限延伸 => no a giant structure
Also, C60 is a molecule. Fullerenes exist as discrete molecules.

Puppet

原帖由 octopus001 於 28-4-2008 12:11 發表
我死的 岩岩做左  得幾條岩.. 聽日chem 冇希望 ..
救救me ....
Q2why D錯?
Q3WHY(1)錯?
Q9WHY(1)錯?
Q10(1)WHY是REDOX
Q14WHY B NOT A?
Q15WHY D? DELTA H

2. Neutral iff [H+] = [OH-]
pH of pure water < 7 at a temp. higher than room temperature.

3.
In groups I and II, the density of metal decreases down the group. Metallic bond strength decreases.

9. Dissolving salts is normally endothermic e.g. KI, NaCl

4.
Cond/Add 係polymerization模式的分法
Thermoplas/Thermoset係對熱soften與否的分法
冇人話Addition唔可以係thermoset

20. The water is formed from neutralization

[ 本帖最後由 Puppet 於 28-4-2008 21:00 編輯 ]