Chemistry

[ameen]

Salam,

SubhanAllah, that is great Br. Ameen. (I take you are a brother, for some reason).

salam,

that is correct, and you are very welcome : )

 

[Arwa]

Salam,

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

wa alaikum assalam

Lol nopes. I remember doing the star cycle in physics for GCSE. :thankyou:

 

[Ameeratul Layl]

wa alaikum assalam

Lol nopes. I remember doing the star cycle in physics for GCSE. :thankyou:

GCSE Physics? Hah, all I remember was the symbol for a light bulb in a circuit.

 

[ameen]

as-salamu'alaikum,

to all students of A-Level Chemistry: if you are able to purchase only ONE book for your course (other than a syllabus-specific book), then I think the 'Complete A-Z Chemistry - Handbook' would be best, because it is like a 'dictionary' of all A-level Chemistry terms and concepts.

So for example, to look up 'homolytic fission', you would simply skip to the letter 'H' category in the book, and look up the 'definition' / explanation:

The book can be purchased at the following link:

http://www.amazon.co.uk/gp/product/0340872713/202-6725321-1523844


wsalam

 

 

[Skillganon]

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:

Concentration = mole /Volume

HxA
Conc = 0.10 mol dm-3


NaOH
Conc = 0.15mol dm3
Volume = 25ml =0.025 L

H+ (Acid)
Conc= ?
Volume= 12.35ml = 0.01235


No of moles H+ = 0.025 x 0.15 = 3.75 x 10-3 moles

Conc of H+ = 3.75 x 10-3 / 0.01235 = 0.30 mol dm-3

HxA concentration is 0.1 mol dm-3 but the acid in the titration gives concentration of 0.3 mo dm3 which is 3 times stronger. x Must be 3.

Hope that helps to clarify it further.

 

[Jayda]

Hola compañeros... I can help if anybody has any biochemistry questions...