Author Topic: Chemistry Help Moles !!! Have been stuck on this one for hours !!! :(  (Read 1668 times)

holtadit

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Okay the question i need hellp on is in paper 4 oct/nov 2007 GCE-O Level.

Go to question 10 (g).

I understand everything from a-f but i dont understand how they get 0.0131 moles for (g). 0.0131 is given in the mark scheme as the answer.

Please help me !! Please Explain how to do question 10 (g) !!

Offline Ghost Of Highbury

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Re: Chemistry Help Moles !!! Have been stuck on this one for hours !!! :(
« Reply #1 on: September 04, 2009, 01:27:57 pm »
okk heres the summary first..

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2NaOH           +          H2SO4  -->  Na2SO4    +   H2O

(26.2 cm3)                (25cm3)
(0.1 mol/dm3)            _____(watever doesnt matter)
0.00262 moles            0.00131 moles
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ok now,
we know that 25 cm3 of acid is 0.00131 moles....
they are just asking what no. of moles will react with 250 cm3..

therefore 25cm3   -   0.00131 moles
             250cm3  -   0.00131 moles * 10 = 0.0131 (ANSWER!!!)

------

some1 plz correct the method if wrong...



divine intervention!

holtadit

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Re: Chemistry Help Moles !!! Have been stuck on this one for hours !!! :(
« Reply #2 on: September 14, 2009, 03:43:58 pm »
Thanks much obliged. :D

Offline Ghost Of Highbury

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Re: Chemistry Help Moles !!! Have been stuck on this one for hours !!! :(
« Reply #3 on: September 14, 2009, 04:25:01 pm »
divine intervention!