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Author Topic: chemistry moles help please ?  (Read 1984 times)

Offline aiyla

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chemistry moles help please ?
« on: October 25, 2009, 03:59:35 pm »
Concentration of cholesterol C27H4O6 in a patients blood was found to be 6 millimole
a. find the concentration in mole/dm3
b. find the concentration in grams/dm3
c. what is the mass of cholesterol in 10cm3 of the patients blood .


please if some one can answer this ,, its not much .. cud u like show what formula;s you used ?
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Offline @d!_†oX!©

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Re: chemistry moles help please ?
« Reply #1 on: October 25, 2009, 04:15:50 pm »
Quote from: aiyla on October 25, 2009, 03:59:35 pm
Concentration of cholesterol C27H4O6 in a patients blood was found to be 6 millimole
a. find the concentration in mole/dm3
b. find the concentration in grams/dm3
c. what is the mass of cholesterol in 10cm3 of the patients blood .


please if some one can answer this ,, its not much .. cud u like show what formula;s you used ?
can u check the question plss
i think the question should be 6 millimole per dm^3 (or litre or cm^3 cuz d concentration cannot be just 6 millimoles)
check the question and let me know
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AAL IZZ WELL!!! ;)

nid404

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Re: chemistry moles help please ?
« Reply #2 on: October 25, 2009, 04:26:12 pm »
Is it 6 millimolar ???
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Offline aiyla

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Re: chemistry moles help please ?
« Reply #3 on: October 25, 2009, 04:44:36 pm »
yes its 6 millimole per dm^3
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nid404

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Re: chemistry moles help please ?
« Reply #4 on: October 25, 2009, 04:47:57 pm »
I assume it is millimolar.
So u get millimolar=10-3 molar
1 molar= 1mol/l
1l=1dm3
therefore
 a)6 millimolar= 0.006 molar or mol/dm3
b)1 mole= 27X12 + 4 + 6X16=424g
therefore 0.006moles/dm3 = 0.006X424g/dm3
c)conc is 0.006mol/dm3. volume=10cm3 which is 0.01dm3
conc=mole/vol
moles=concXvol
so no of moles of cholestrol in 0.01dm3 are 6X10^-5

hope this helps :)
therefore mass is 6X10^-5 X 424

« Last Edit: October 25, 2009, 05:12:59 pm by nid404 »
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Offline aiyla

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Re: chemistry moles help please ?
« Reply #5 on: October 25, 2009, 05:08:20 pm »
thanks aalot ... thats the way i wanted it ..

but in the end u multiplied by 242 instead of 424



<3
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nid404

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Re: chemistry moles help please ?
« Reply #6 on: October 25, 2009, 05:12:37 pm »
Quote from: aiyla on October 25, 2009, 05:08:20 pm
thanks aalot ... thats the way i wanted it ..

but in the end u multiplied by 242 instead of 424



<3

oh im sorry abt that...haste leads to waste...I'll edit my post
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Offline aiyla

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Re: chemistry moles help please ?
« Reply #7 on: October 25, 2009, 05:40:24 pm »
how did u convert 6 millimolar to 0.006 mol/dm3

i dont get that part ):
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Offline aiyla

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Re: chemistry moles help please ?
« Reply #8 on: October 25, 2009, 05:48:47 pm »
i got the first part ,, but here this in the second one

0.006X424g/dm3

why did we multiply instead of divide ? 
to find g/dm^3  isnt it  .. mass of solute/volume of solution  ????
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nid404

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Re: chemistry moles help please ?
« Reply #9 on: October 25, 2009, 06:45:56 pm »
Quote from: aiyla on October 25, 2009, 05:48:47 pm
i got the first part ,, but here this in the second one

0.006X424g/dm3

why did we multiply instead of divide ? 
to find g/dm^3  isnt it  .. mass of solute/volume of solution  ????

we r simply converting moles to gms. so u just multiply the moles by the mass of 1 mole.

mass= no.of moles X molar mass
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