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Author Topic: MOLES question.  (Read 1723 times)

Offline nonelee

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MOLES question.
« on: June 02, 2009, 10:14:10 am »
i am taking coordinated science this week.
and i have a question please answer (:

theres a formula for calculating moles right?
but i forgot, please tell me.
and there are also something else related to moles.
i forgot too. so again, please answer. thanks!
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Offline idk

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Re: MOLES question.
« Reply #1 on: June 02, 2009, 10:26:19 am »
Number of moles=given mass of substance divided by( / ) atomic or molecular mass of the substance.
for eg-given mass  of a piece of coal(carbon)=24g. at.mass of carbon=12
therefore number of moles=24/12=2 moles
best of luck and Take care.
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Q80BOY

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Re: MOLES question.
« Reply #2 on: June 02, 2009, 10:30:40 am »
finding the mole using the realative atomic mass:

mole = mass used / relative atomic mass

finding the mole of a compund:

mole = mass used / relative molecular mass

finding the mole in a solution:

mole = volume (dm^3) * molarity

finding the mole of any gas:

mole = volume (dm^3) / 24 dm^3

finding the percentage yield:

% yield = (mass produced / theoretical yield) * 100

finding the percentage purity:

% purity = (actual mass reacted / initial mass used) * 100

hope this helps  :)

« Last Edit: June 02, 2009, 10:35:58 am by Q80BOY »
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Offline nonelee

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Re: MOLES question.
« Reply #3 on: June 02, 2009, 10:34:43 am »
thank you people :D
but i remember theres this formula which needed volume?
i forgot..
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Q80BOY

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Re: MOLES question.
« Reply #4 on: June 02, 2009, 10:36:21 am »
Quote from: nonelee on June 02, 2009, 10:34:43 am
thank you people :D
but i remember theres this formula which needed volume?
i forgot..

i added it  ;)
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Offline nonelee

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Re: MOLES question.
« Reply #5 on: June 02, 2009, 10:37:19 am »
thanks again (:
do you take coordinated science too?
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Q80BOY

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Re: MOLES question.
« Reply #6 on: June 02, 2009, 10:38:56 am »
Quote from: nonelee on June 02, 2009, 10:37:19 am
thanks again (:
do you take coordinated science too?

nope, i take the normal chemistry :)
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Offline nonelee

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Re: MOLES question.
« Reply #7 on: June 02, 2009, 11:12:54 am »
oh...why? like a lot of people are taking them separately.
which one is harder you think?
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Q80BOY

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Re: MOLES question.
« Reply #8 on: June 02, 2009, 11:14:51 am »
Quote from: nonelee on June 02, 2009, 11:12:54 am
oh...why? like a lot of people are taking them separately.
which one is harder you think?

im not sure, i know nothing about co-ordinated science, and my school were not offering it as an option.

thanks  :)
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Offline nonelee

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Re: MOLES question.
« Reply #9 on: June 02, 2009, 11:16:58 am »
oooh okay. (: thanks again.
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Q80BOY

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Re: MOLES question.
« Reply #10 on: June 02, 2009, 11:18:00 am »
Quote from: nonelee on June 02, 2009, 11:16:58 am
oooh okay. (: thanks again.

no worries,

and gd luck in ur science exam  :)
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Offline nonelee

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Re: MOLES question.
« Reply #11 on: June 02, 2009, 11:23:55 am »
oh let me ask one more.
whats the formula for resistance?
is it voltage/current? or the opposite?
im confused..
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Q80BOY

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Re: MOLES question.
« Reply #12 on: June 02, 2009, 11:27:55 am »
Quote from: nonelee on June 02, 2009, 11:23:55 am
oh let me ask one more.
whats the formula for resistance?
is it voltage/current? or the opposite?
im confused..

that's ohm's law,

resistance = voltage / current
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