Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 357623 times)

Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #225 on: November 15, 2009, 02:44:18 pm »
Thanks Aadi. I tried balancing it earlier but the cud not do it properly Thanks 4 xplainin!

@Aditoxic Thanks 4 ur help 2
lol...dude aadi wanted his to be changed but y u changed mine...lol...bt anyways..its kk...i dont mind at all
AAL IZZ WELL!!! ;)

Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #226 on: November 15, 2009, 02:54:28 pm »
thanks man! all ready for chem?
divine intervention!

Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #227 on: November 15, 2009, 02:56:38 pm »
yeah dude!!!just finished up with some past papers...nd all set to rock it...haha....i wanna come back nd write "expecting 40/40" inthe thread tom too
bt i dont think i wud write dt b4 7-8 tom...gonna have a P-A-R-T-Y!!!!!!! :D :D :D :D
AAL IZZ WELL!!! ;)

Offline ~~~~shreyapril~~~~

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #228 on: November 17, 2009, 06:40:22 pm »
NJOY THE PARTY>>>>!!
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #229 on: December 21, 2009, 11:31:28 am »
2009 may paper 3 Question 5 b

How is it done ? They ER says:

The crucial point of the calculation is to realise that 8 cm3 of the
phosphate solution reacted with 12 cm3 of an aqueous solution of the nitrate of metal T. This can
be deduced from the graph.

Where does it say this on the graph ?

nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #230 on: December 21, 2009, 11:37:18 am »
check the X axis of the graph...the solution contains 8 cm3 of phosphate that has reacted....the volume of the solution, after this point is constant(which implies that only 8cm3 of phosphate has reacted)

holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #231 on: December 21, 2009, 11:41:27 am »
could u show me the steps please.

nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #232 on: December 21, 2009, 11:43:14 am »
could u show me the steps please.

for the b) part right? like the formula of the compound?


holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #233 on: December 21, 2009, 11:45:54 am »
like how would u do it with a proper explanation. I want to know exactly what your thinking and doing when u solve for the formula.

nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #234 on: December 21, 2009, 12:31:38 pm »
sorry for taking so long...some important calls
Anyway

Na3PO4+ nTx(NO3)y----> NaNO3+ Tnx(PO4)z

all the variables are unknown at present

U know the reaction will give sodium nitrate which has the formula NaNO3[/sub]....now u also know the volume of the product is 8cm3
the volume of sodium phosphate is 2cm3...
The mole ratio of sodium phosphate and Tnitrate is 2:3, when u try to balance for NaNO3...and u get (NO3)2. The product side has 6NaNO3
This gives us the charge on T as +2...since (NO3)2-...u know PO4 will be twice and thus T will be thrice cuz of the charges
 
Little weird to understand...ill put down the balanced equation, which is likely to make it easy for u to figure it out

2 Na3PO4+ 3 T(NO3)2---->6NaNO3+ T3(PO4)2

I'll try explaining again...i tried my best to explain tho...


holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #235 on: December 21, 2009, 01:06:28 pm »
so whats your final answer. what is the formula of the phosphate

nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #236 on: December 21, 2009, 01:47:06 pm »
so whats your final answer. what is the formula of the phosphate

T3(PO4)2 as given in the final equation

Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #237 on: December 21, 2009, 01:58:59 pm »
thanks nid :)
AAL IZZ WELL!!! ;)

nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #238 on: December 21, 2009, 02:16:17 pm »

holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #239 on: December 29, 2009, 07:21:58 am »
IGCSE Paper 3 Question 4 (b) (ii)

It says draw the new graph. How do u know where to draw the graph till. In the ms it says it should be drawn till 8cm3. How do u obtain this value and why this value ?

Help and plz explain well !!