help with moles


by hamxa7
Tags: moles
hamxa7
hamxa7 is offline
#1
Oct19-11, 03:05 AM
P: 4
can someone clear my concepts about these two equations ???

Equation 1... Concentration(g/dm3) = Concentration (Mol/Dm3) % Mass Of 1 Mole Of Solute

Equation 2... Number Of Moles Of Solute=Concentration(Mol/Dm3) x Volume In Cm3 % 1000cm3

reply quickly.. got my chem school exam tommorow...
Phys.Org News Partner Chemistry news on Phys.org
Patented research remotely detects nitrogen-rich explosives
Pocket-sized anthrax detector aids global agriculture
Structure of sodium channels different than previously believed
Borek
Borek is offline
#2
Oct19-11, 03:20 AM
Admin
Borek's Avatar
P: 22,666
Hard to tell what you want to clear not knowing what your concepts are.

I guess by % in the second equation you mean division, although the same % in the first equation is placed where the multiplication should be:

[tex]C [\frac {g} {dm^3}] = C [\frac {mol}{dm^3}] \times M_m [\frac {g} {mol}][/tex]

where Mm is a molar mass.

So, what is your problem (apart from procrastination)?
hamxa7
hamxa7 is offline
#3
Oct19-11, 04:27 AM
P: 4
I wanted to know how are they are evolved...
Answering a problem regarding the equations woud be appreciated...

Borek
Borek is offline
#4
Oct19-11, 04:40 AM
Admin
Borek's Avatar
P: 22,666

help with moles


You have to be more specific, at the moment I have no idea what you are interested in - you question is ambiguous and way too vague.

By evolved - do you mean derived? If so, the second is just a a molar concentration definition solved for n, and with a mL <-> L conversion factor added. First can be obtained combining definition of molar concentration and definition of molar mass.
jetwaterluffy
jetwaterluffy is offline
#5
Oct19-11, 05:28 AM
P: 227
1dm3=1000cm3. The 1000 is just a conversion factor. Equation triangles helped a lot with me. (But volume has to be in dm3)
......^
..../mol\
/vol*conc\
You use an equation triangle by covering up the quantity you want to work out. That leaves an equation to work it out using the other two.
Also:
.....^
../mass\
/mol*Mr\
and
.....^
.../vol\
/mol*24\
Borek
Borek is offline
#6
Oct19-11, 06:12 AM
Admin
Borek's Avatar
P: 22,666
Quote Quote by jetwaterluffy View Post
Equation triangles
Bastardized way of dealing with equations when you don't know basic algebra. It is really much better to learn general method of solving the equation for an unknown, than to memorize particular approach to particular problem.


Register to reply

Related Discussions
How many moles of XYZ Biology, Chemistry & Other Homework 1
moles of Ir to kg Introductory Physics Homework 5
Help finding moles of pain killer/moles of hydrogen ion in a pain killer w/ titration Biology, Chemistry & Other Homework 3
moles Advanced Physics Homework 14
What is the mass of one mole of aluminum? Biology, Chemistry & Other Homework 3