Understanding Equations for Chemistry Exam Prep

AI Thread Summary
The discussion centers on clarifying two equations related to concentration and moles in chemistry. The first equation relates concentration in grams per dm³ to molarity and the molar mass of the solute, while the second defines the number of moles based on concentration and volume, incorporating a conversion factor from cm³ to dm³. Participants emphasize the need for clarity in the original query, noting that the use of "%" in the equations may cause confusion, as it typically denotes division rather than multiplication. They suggest that the first equation can be derived from the definitions of molar concentration and molar mass, while the second is a rearrangement of the molar concentration formula. The discussion also touches on the utility of equation triangles as a visual aid for solving these types of problems, although there is a caution against relying solely on memorization of specific methods without understanding the underlying algebraic principles.
hamxa7
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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...
 
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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:

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

where Mm is a molar mass.

So, what is your problem (apart from procrastination)?
 
I wanted to know how are they are evolved...
Answering a problem regarding the equations woud be appreciated...
 
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.
 
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\
 
Last edited:
jetwaterluffy said:
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.
 
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