Chemistry Paper 2 discussion =)

[Prince III]

can anybody tell the questions & answers of complete question number 1 from section A (paper22)

1. name the metal which forms alkaline solution in water
A. pottasium (k) fisrt group metals are called alkali metals

2.name the metal which forms oxide layer
A . aluminium

3.name a metal which rust it self to protect the other metal from rusting
A . magnisium

4.name a metal from period V
A.silver (Ag)

this is all i could remember


(b) structure of typical metal and labeling

i wrote magnesium for the alkaline one. Mg reacts with H2O to form Mg(OH)2 which is also alkaline as its a hydroxide,right? I hesitated to use potassium cause i thought reaction wud be explosive,lol.

both would be correct altough magnisum reacts with water very very slowly unless magnisium is hot
altough potassium reacts voilently with water with flames but after some seconds when the flames stops , hydrogen gas is released leaving behind alkaline soluntion

2K(s) + 2H20(l) = 2KOH(aq) + H2(g)

 

[Prince III]

The very last question.
SO2 + O2 <==> SO3
What is the effect of increase in temperature?
(I forgot the exact question).
I said that more SO2 and O2 will be produced.
Is that correct?

as the reaction was exothermic , if we increase the temperature equlibrium would shift to that side there the heat is being abored , so equlibrium would shift to left hand side . that means SO3 would start breaking up to form O2 and SO2

 

[rose1700]

please tell the correct answer for the moles question in section A
we have to find the concentration

and there was another question on section B where we have to find mass in gram of something


and guys wat was the emiprical formula below the dot and cross diagram of CO

was it CrO6H6 ??


or some something like that please respond quick !

 

[Zeuss]

please tell the correct answer for the moles question in section A
we have to find the concentration

and there was another question on section B where we have to find mass in gram of something


and guys wat was the emiprical formula below the dot and cross diagram of CO

was it CrO6H6 ??


or some something like that please respond quick !

Hey, umm, the mass was 5.1 i think..and u got the empircal formula correct..and the concentration was 2.25 x 10^-3

 

[Prince III]

please tell the correct answer for the moles question in section A
we have to find the concentration

and there was another question on section B where we have to find mass in gram of something


and guys wat was the emiprical formula below the dot and cross diagram of CO

was it CrO6H6 ??


or some something like that please respond quick !

concentration = 0.0023 mol/dm^3 (or) 2.25 x 10^-3 mol/dm^3

mass = 5.1 g


and the emiprical formula was crO6H6

atough Zuess have answer you but just wanted to reconfirm to you and other !

 

[rose1700]

Name the organic compound needed for fermentation

guys wont ethane be the correct answer for this because as far as i could remeber steam was adding in the organic compound


howcome glucose could be the answer :/

 

[Pals_1010]

Hey rose ,

The answer cannot be ethane as ethane is an alkane and doesn't react with steam.

The answer can neither be ethene as the addition of ethene to steam is known as a hydration reaction

Fermentation is when a mixture of glucose and yeast is left to stand in anaerobic conditions at around 37 degrees celcius to from ethanol.

Glucose is a also an organic compound because of the presence of carbon in it. It is a natural organic compound

Hope that helped

 

[rose1700]

ohh ! yes you are right
thanks that would be helping me next time

do you remeber the numbers for all the parts of this question ?

 

[axhynic]

instead of glucose, how about yeast?

 

[bamteck]

Instead of ethyl ethanoate, can't it be ester?

 

[Tichouk Chan]

I don't think ester will be accepted!maybe you can be given half a mark!!um btw i got a small question! in section B the question on sulfur dioxide n effect of temp on equilibrium...i forgot to write about effect of increasing temp on the yield of SO3!!umm you think i may lose marks???

 

[Prince III]

I don't think ester will be accepted!maybe you can be given half a mark!!um btw i got a small question! in section B the question on sulfur dioxide n effect of temp on equilibrium...i forgot to write about effect of increasing temp on the yield of SO3!!umm you think i may lose marks???

mainly question required to state that where the equlibrium would shift
it was better if you mentioned that so3 starts to break into o2 and So2

but hpefully no marks would be deducted

 

[Pals_1010]

Hey guys,

For the first question in Section B,

Do you remember the question and how you answered it?

It was something about regulation of carbon dioxide in the atmosphere i think?

 

[axhynic]

edit : instead of glucose, could yeast be a correct answer?

 

[sobaa]

wow...paper was awsomee....EXPECT THE UNEXPECTED..!!

 

[ShaffaanVen]

and hey was carbon monoxide in our syllabus??? Because the structure involved dative bonding!!! any idea?

Thx Prince

yes you are right this was out of sylabuss because this is quite advance bonding known as dative covalent bonding

But i have askhed one of chemistry sir , he said that examiner would be looking for just " tripple covalent bond" to give full marks
so basically , this question was to test that is a candidate able to draw a tripple covalent bond and does he / she know that in tripple covalent bond 6 electrons are shared

so we just have to share 6 electrons between them and the rest of electrons still revolving in the shells

see the below diagram
this would be accepted

Most Probably!
Dative covalent bonding! =)
The gr10s were asked this same question in the 1st semister exams by mistake. They removed it later! Haha!
PS: I'm from gr9
I think its as follows! =D

 

[Prince III]

maybe i guess ShaffaanVen made the correct dot and cross diagram
but as this was out of sylabuss i guess examiner would give us credit too
lets hope for the best

 

[Shiki Misaki]

If this is out of syllabus, nobody will be penalised. Instead we will earn those three marks (hopefully).

 

[Heshna]

@ shiki : Even if its out of syllabus, many Mauritian students got the answer...now it depends on Cambridge...Hope that we are not penalized...

 

[Shiki Misaki]

Well yeah, it all depends now.