Chemistry paper 31 (NEW)

[NOOB12345]

I wrote for question 7b, that metal B produce more hydrogen because:

Aluminium has valency of 3 and Chlorine of 1, the formula for Aluminium Chloride is AlCl3, where as for the other 2 metals is MgCl2 and ZnCl2. Therefore 1 Mole of Aluminium will react with more moles of HCl than Zinc and Magnesium, hence producing more hydrogen.

and I wrote the same/similar for 7a where you have to identify metal and explain. Don't know if this will score me the explanation for why Metal B is Aluminium. (I heard many people explained metal B using reaction rate and oxide layer) I hope mine is an alternative answer... And btw why is 7a, the identification and explanation of metals only 5 marks? (I thought it would be 3 pairs of marks)

and what did you write for the explanation for the 2 other metals?

 

[farhan143]

exactly ur right! i did he same thing

 

[nightwalker221]

Yeh, i wrote something like that aswell, and what did you write in the Molecular formula thing.
I wrote CHO.

 

[AhmedNES]

is acid concentration is 1.33

 

[Ashique]

I simply wrote that there are more moles of Aluminium present due to the presence of the oxide layer, and few number of moles in cae of Mg and Zn.. So more moles of Al producing more H2

 

[nightwalker221]

Yep thats what i wrote as well

 

[DowntownCrew]

The selenium one was that it is acting as a reducing agent because it removes the Oxygen from the what ever the reaction was. I forgot it.

I did the same.

is acid concentration is 1.33

I put the same , but really not sure about it...it was a guessing


About A,B,C and hydrogen - would reactivity series be helpful ? They mention how metals react with hydrogen and even there was an order from those who react most to those who react the least... I also put the same like you guys , with help of that table.

 

[ssms396]

can someone tell me what the MOLES question was....i dnt rely remember any moles question....
and there was one with defining fermentation in simple terms....wut did u write?

 

[NOOB12345]

Since it said define in general terms of the term 'fermentation' I wrote:

Fermentation is the process of making alcohol by using Bacteria (CO2 as side product), through anaerobic respiration.

I should have been more specific though, for example naming the alcohol (ethanol) and use yeast instead of bacteria. Probably lost some marks there...

The chemistry this year feels like biology.

 

[nightwalker221]

I think that much is enough, but it was for 4 marks so 4 main points to be written.
I wrote:
Process of making alcohol by the breaking down of sugar with the help of a catalyst called Yeast and the release of CO2 and this process is done by using aerobic conditions.

 

[Gunner1995]

That would have been PERFECT, if u didnt say aerobic .its anaerobic

 

[ssms396]

I think that much is enough, but it was for 4 marks so 4 main points to be written.
I wrote:
Process of making alcohol by the breaking down of sugar with the help of a catalyst called Yeast and the release of CO2 and this process is done by using aerobic conditions.

i wrote pretty much the same thing but i wrote breaking down on "FOOD" instead of "SUGAR".... i wuz going to write sugar...but i just didnt.....I FEEL LIKE A LOSER!!!! i hate it when we know the rite answer but chose something else in the end!!!! :x

 

[MAK1995]

come on ppl it wasss sooooo easyyyyyyy :O

 

[adityar]

If I remember correctly, the graph description is like this:
There's 3 lines, one of them goes less steep at first then gets more steep and finishes at more volume of hydrogen. I made it Aluminum as there's an oxide layer that prevents it from reacting fast at first as an explanation.
The other 2 have same volume of hydrogen but one of them was more steep. More steep is Magnesium, the other is zinc.

Are you listening to yourself?! How could Al form an oxide layer, WHEN IT WAS SUBMERGED IN CONCENTRATED ACID?! Even if it was dilute, there would be hydroxide ions, NOT OXYGEN.