Chemistry

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I created this specially for us Chemistry ppl. Anyway, i follow OCR, and any1 has practical exam coming up soon?

Well,this thread is just for discussion of chemistry. Help with chem, etc

I have a go, any1 know this:

A titration was carried out using an 0.10 moldm-3 solution of an unknown acid, HxA to determine the value of ‘x’ in the acid formula. 25 cm3 of 0.15 moldm-3 sodium hydrogen carbonate solution was found to require an average titre of 12.35 cm3 of acid to just neutralise it. What is the value of x?

Well, the answer is this:
1. Amount of sodium hydrogen carbonate = 3.75 x 10-3 mol,
ratio is 1:1, so amount H+ = 3.75 x 10-3 mol
H+ is 0.3 moldm-3, so x=3

any idea how they got that? :zip:
 
Assalamu'Alaykum

Molar concentration of the acid was 0.1M, yet it react as if it was 0.3M - the only possible explanation is that it contains three protons per particle.


hope that clears it up for u
 
3washey said:
Assalamu'Alaykum

Molar concentration of the acid was 0.1M, yet it react as if it was 0.3M - the only possible explanation is that it contains three protons per particle.


hope that clears it up for u
Click to expand...

did you know you sounded just like a College proffesor ???? (no sarcasm) :)lol
 
Lol...I'm doing A2 Chemistry, I think its quite hard, probably because I really dont like it. Anyway, I'm so glad I've got my CW out of the way... I just thought I'd express my relief!!! :D

Wassalam
 
Molar concentration of the acid was 0.1M, yet it react as if it was 0.3M - the only possible explanation is that it contains three protons per particle.
Click to expand...
:sl:
sorry,but have absolutely no idea what u r talking about ???
 
praise be to Allah and the prophet Mohammed. continue to send more chemistry questions if you can. :) :thumbs_up :applaud:
 
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Assalamu"Alaykum

Danish said:
:sl:
sorry,but have absolutely no idea what u r talking about ???
Click to expand...


ok Bismillaah...

Molar concentration of acid was given - it was 0.1M

Such an acid should be able to neutralize some amount of hydrogen carbonate - but it neutralizes more. So it must have more than one proton reacting.
 
ahmed687 said:
did you know you sounded just like a College proffesor ???? (no sarcasm) :)lol
Click to expand...


Assalamu'Alaykum,

Subhanallah, but did u understand what i posted?
 
Salam,

I will be doing A2 when college begins again.

If anyone needs AS help, you are more than welcome to ask.:)

Wasalam
 
Salam,

Could anyone explain homolytic fission and the star theory.
I have forgotten it. I have read through my textbook but there is too much.

Wasalam
 
salam,

According to my Nuffield Chem. book, summarised in two sentences:


Homolytic fission is when UV (Ultraviolet) light is used / absorbed by a molecule such as chlorine (Cl-Cl ), to 'split' it into two atoms (Cl and Cl), each with an odd number of electrons on the outer shell.

This is different to the formation of ions following the gain and loss of electron/s by each atom, because in this case, a covalent bond is broken, with each atom in the bond taking one electron, to form two 'free-radicals'.

Please ask if I can clarify further.


Also, when you say 'star theory', are you talking about the life cycle of stars?

If so, is that not covered in the Biology syllabus (not Chemistry) ?

 
 
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Ameen- said:
salam,

Please ask if I can clarify further.

In that case, could you add diagrams to your theory. I understand diagrams better than the theory.


Also, when you say 'star theory', are you talking about the life cycle of stars? :S
Correct

If so, is that not covered in the Biology syllabus (not Chemistry) ?I have not yet come across it in the Biology book but it is in the chemistry book

*
Click to expand...

JazakAllah for your help so far.

:w:
 
salam,

well, this is basically what happens when a chlorine molecule absorbs UV light:


View attachment 2076


do you see how the covalent bond in the middle (left-hand side) is broken and the molecule is split into two identical free-radicals (right-hand side) ?

It's called 'homolytic fission' because 'homo-' is from the Ancient Greek meaning 'same' and 'fission' because the molecule splits.


wsalam
 
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wa alaikum assalam

Also, when you say 'star theory', are you talking about the life cycle of stars?

If so, is that not covered in the Biology syllabus (not Chemistry) ?
Click to expand...

Isn't it physics? ^o)
 
salam,

yes, I was wrong. According to my book, it's Physics, under the topic - 'Forces', but it's probably Chemistry as well, since it's in sr. ameeratul layl's chemistry-book.

 
 
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salam,

the following short summary of the life-cycle of a star is from a GCSE book, but still may have relevance to A-level:


star_cycle.jpg

 
 
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Salam,

SubhanAllah, that is great Br. Ameen. (I take you are a brother, for some reason). It is so consice and to the point. Just what I need.
Sister Arwa, the star life cycle has not been mentioned in my AS Physics lessons. But, it sure has been mentioned in Chemistry. Do you study Physics?

Wasalam
 

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