Chemistry Paper 22 3rd Nov

[Deadly_king]

I think i drew it correctly. i wrote bent cos there's lone pair(which i know- its wrong now), its okay.. but why is it linear, is it because as long as there's 2 bond pair, its linear? ignore the lone pairs? (trying to learn, paper 1 left).. 

C=C=O

Nope, the lone pairs are found on the extreme atoms namely : oxygen and carbon on the left.

Both of them carry a double bond which are taken as one since they go in the same direction.

Hence in whichever direction the lone pairs repel the bond pairs, it won't have any effect.

However if the lone pair had been found on the carbon atom in the middle, then it would have been bent.

[cs]

Yes i am correct! hehe, i drew the structure out, comparing H2O and CO2, found out that the difference is the middle atom, Thank you Deadly King, i am sure you will do well in your exam.. you're so good!

[Deadly_king]

Yes i am correct! hehe, i drew the structure out, comparing H2O and CO2, found out that the difference is the middle atom, Thank you Deadly King, i am sure you will do well in your exam.. you're so good!

Hehe............glad you got it well

Anytime...............i really hope so

[Hypernova]

Ooh...........I never expected this kind of question. I messed it up in the beginning but then I finally resolved it.

Hmm.........my answers are :
i) Oxygen - 20 cm³ has been used
ii) Carbon dioxide - 10 cm³ has been formed.

A was methane CH₄

Did we have to find the Mr in that

Do you remember how many marks this question was worth?

[Deadly_king]

Do you remember how many marks this question was worth?

Hmm...........can't remember exactly.

But I guess the whole number should have been 5 marks.

Why are you asking?

[Hypernova]

That was the only one that i can remember that i got wrong,
I made a stupid mistake somewhere.

I've been going over it again and again in my mind, but don't know where I messed up.

I'm impatiently waiting for the marking schemes to get out

[Deadly_king]

That was the only one that i can remember that i got wrong,
I made a stupid mistake somewhere.

I've been going over it again and again in my mind, but don't know where I messed up.

I'm impatiently waiting for the marking schemes to get out

Hey don't worry about it now.

You'll only harm yourself by thinking about it over and over again. you won't be able to change anything now. What's already happened cannot be changed. Just chill a bit and concentrate for the rest of your papers.

I think i made some minor mistakes as well

[$!$RatJumper$!$]

aw dnt worry about it bro.. DK is right, thinking about it cannot change a bit of anything now isnt it. i know how tempting it is to go over the exam in ur head and remember what u got wrong, but whats the point. if it makes u feel better, i didnt manage to get the formula of CH4 nor the volume of the 2 gases. thats like 5 marks gone already. but it doesnt matter one bit because as long as i know i did well in the rest of my paper i feel im getting an A DK, which questions do you think u got wrong?

[Deadly_king]

aw dnt worry about it bro.. DK is right, thinking about it cannot change a bit of anything now isnt it. i know how tempting it is to go over the exam in ur head and remember what u got wrong, but whats the point. if it makes u feel better, i didnt manage to get the formula of CH4 nor the volume of the 2 gases. thats like 5 marks gone already. but it doesnt matter one bit because as long as i know i did well in the rest of my paper i feel im getting an A DK, which questions do you think u got wrong?

Hmm...........the two processes of cracking
I was aware of only one process.

The last number as well.............hydrogen hallide. Am not sure about the answers.

[Hypernova]

In cracking, one process uses heat, and the other uses a catalyst...right?
The one using heat make a hard polymer, and the one using a catalyst makes a soft polymer like plastic bags.

X was I₂ right...so the halide was HI

Did you guys get the same?

[Hypernova]

or was it Br₂?

[$!$RatJumper$!$]

I got my two processes as:

1) Thermal Cracking- Uses 400-900 degrees celsius, 70 atm
2) Catalytic Cracking- Uses 450 degrees celsius, >1 atm, Zeolite Catalyst

For the last question my answers were:
 
NaBr
Br₂
Sulphuric Acid acts as a much better oxidizing agent

What did you guys get?

[Hypernova]

But we didn't have to mention conditions, right?
Just saying Temp and catalyst should've been fine. Wasn't that 2 marks?

[Deadly_king]

But we didn't have to mention conditions, right?
Just saying Temp and catalyst should've been fine. Wasn't that 2 marks?

Nope.

The question actually asked for the conditions of the two different processes.

I didn't know about thermal cracking.
My answers were :
1. Catalytic cracking ---> Temp : 500 and catalyst aluminium oxide

2. Temp : 600 and Silicon dioxide.

Those are similar processes but my teacher somehow told me it might be good. I doubt it though

The last question, i also opted for bromine.

But the other gas, whether sodium bromide or iodide, would have been sulfur dioxide.