Chemistry paper 3 Discussionnnnn

[saifeddin]

anyone ready 100% for it? post any doubts or any questions u have here

 

[SherlockHolmes221B]

I'm terrified of Stochio >.<

 

[shazmina]

Perhaps....

 

[omaaaar]

Problems in endothermic and exothermic questions

 

[Princess Raven]

when they say the solution is aques....is it conctrated or dilute? like how do we know?

 

[omaaaar]

It will be mentioned

 

[walkanwine]

this paper will be difficult and no matter how good you are in chemistry it will be a bit of a challenge. may God help us all

 

[Princess Raven]

It will be mentioned

sometimes its not though.. so um how do we know?

 

[Ibtizam]

I'm terrified of Stochio >.<

me 2

 

[nothing]

this paper will be difficult and no matter how good you are in chemistry it will be a bit of a challenge. may God help us all

No it is not difficult if you study good

 

[LeenBuscus]

I'm worried about polymers mostly

 

[omaaaar]

That is easy just remember the monomers

 

[Rola]

Can anyone post notes on Organic Chemistry please ?

 

[LeenBuscus]

You're probably right but there are polymer names to learn like polyacrylonitrile and such... and I am NOT good at memorizing.

 

[Othman]

Did anybody see the moles question in May/June 2007 ? Can someone help me ?
Page 13; http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_3.pdf

 

[Omar Haider]

Did anybody see the moles question in May/June 2007 ? Can someone help me ?
Page 13; http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_3.pdf

This questions is pretty easy if you look at it. I solved it below.

(d.) Part 1: How many grams of Iodine react with 884g of fat?

Well, 100g react with 86.2g (given in question) so cross-multiply.

(884*86.2)/100 = 762g. (which react with 884g of fat).

Part 2: One mole of fat reacts with how many moles of Iodine molecules?

The keyword in this question is molecules. We know that Iodine exists in the diatomic form meaning it would be I2. One Iodine atom has the Atomic mass of 127 so if you multiply that by 2 (I2) you get 254.
To find the number of moles you the formula = Mass/Mr.
Our mass of Iodine is 762g (found in Part 1). Divide this by 254 and you get 3 moles. If you get 3 moles, that means there are 3 bonds.
Hope I helped!

 

[Othman]

This questions is pretty easy if you look at it. I solved it below.

(d.) Part 1: How many grams of Iodine react with 884g of fat?

Well, 100g react with 86.2g (given in question) so cross-multiply.

(884*86.2)/100 = 762g. (which react with 884g of fat).

Part 2: One mole of fat reacts with how many moles of Iodine molecules?

The keyword in this question is molecules. We know that Iodine exists in the diatomic form meaning it would be I2. One Iodine atom has the Atomic mass of 127 so if you multiply that by 2 (I2) you get 254.
To find the number of moles you the formula = Mass/Mr.
Our mass of Iodine is 762g (found in Part 1). Divide this by 254 and you get 3 moles. If you get 3 moles, that means there are 3 bonds.
Hope I helped!

Thank you.

 

[Rola]

I'm scared about organic chemistry coming up... remembering structures and all that. Oh and redox reactions. Good luck everyone! :'/

 

[LeenBuscus]

I'm scared about organic chemistry coming up... remembering structures and all that. Oh and redox reactions. Good luck everyone! :'/

me too... especially about esters and carboxylic acid stuff
But the Redox reactions can be quite easy as soon as you understand them :I

 

[oahmed64]

i have a problem with the chemical reactions chapter
so when the get u a graph of a rate of reaction and they say sketch the graph of the same experiment using a more concentrated acid for example,when do we join the two graphs (same end volume of hydrogen for example) and when do we not?​