• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Chemistry: Post your doubts here!

qwertypoiu

qwertypoiu

Messages
924
Reaction score
1,096
Points
153
Zash Riyash said:
The shell of a chicken’s egg makes up 5% of the mass of an average egg. An average egg has a


mass of 50 g.

Assume the egg shell is pure calcium carbonate.

How many complete chicken’s egg shells would be needed to neutralise 50 cm3 of 2.0 mol dm–3

ethanoic acid?
Click to expand...
So we are neutralising ethanoic acid using calcium carbonate:
2CH3COOH + CaCO3 --> (CH3COO)2Ca + H2O + CO2

Moles of ethanoic acid = 50/1000 * 2 = 0.1mol
Moles of CaCO3 required = 0.1/2 = 0.05mol
Mass of this CaCO3 = 0.05*Mr(CaCO3)= 5g

So we want 5g of eggshell.
Mass of average eggshell = 50g*5% = 2.5g
Number of eggshell required = 5/2.5 = 2 eggshells

Hope that was helpful :)
 
A

AnonymousX9

Messages
132
Reaction score
46
Points
38
I don't understand the concept behind s,p,d sub-shells and orbitals and also the Aufbau principle. Can any please explain the basics?
 
qwertypoiu

qwertypoiu

Messages
924
Reaction score
1,096
Points
153
AnonymousX9 said:
I did and I still don't understand it properly. :(
Click to expand...
Well I'll be straight with you. That website, chemguide, is one of the best websites I've seen for chemistry. In fact, you can rely just on this one website for all your a level needs. However, it is true that students have different learning types. Some are visual learners, others need ppl to explain orally, etc.
I think it's difficult to explain whole concepts by typing here. You should go talk to your teacher. Go sit down with him and let him explain everything till you get it. Or perhaps a knowledgeable classmate. Or a senior student. Hope you learn it well :)

PS. If there is a specific paragraph from the link you didn't understand, just quote it and explain what you don't get, I'll try my best to elucidate.
 
P

psychiatrist

Messages
69
Reaction score
82
Points
28
Metanoia or anyone else, help me remembering As level inorganic stuffs, that are chapters, Periodicity, Group II and VII and sulfur and nitrogen...
Just temme what is importantand what is the trick to remember those stuffs. Thanks.
 
Metanoia

Metanoia

Messages
603
Reaction score
1,102
Points
153
psychiatrist said:
Metanoia or anyone else, help me remembering As level inorganic stuffs, that are chapters, Periodicity, Group II and VII and sulfur and nitrogen...
Just temme what is importantand what is the trick to remember those stuffs. Thanks.
Click to expand...

Its not easy to say what is important or not.

Its best for you to look through the objectives listed for the respective chapters and make sure you understand the requirements.
http://www.cie.org.uk/images/128593-2015-syllabus.pdf

If any objective seems unfamiliar, its an indication you need to revise that particular concept.
 
You must log in or register to reply here.
Top