C%w/w = msubstance / msubstance + msolvent x100 (definition of percent concentration)

[Chemist98]

C%w/w = msubstance / msubstance + msolvent x 100%

 

What is the formula to solve for msubstance?

[thedarkshade]

Could you please be more specific on your question, and than you might get some help. I personally find it hard to understand what you really need in this case!!!

[Cap'n Refsmmat]

He's trying to solve the equation

 

[math]C\% = \frac{ m_{\mbox{substance}} } { m_{\mbox{substance}} + m_{\mbox{solvent}} } \times 100[/math]

 

for m_substance.

 

All it takes is some fancy algebra, or an equation solver on a decent calculator.

[thedarkshade]

If you're asking for this [math]m_substance[/math] that is in the equation that Cap'n posted than you just need tot follow simple mathematical steps!

[Chemist98]

Would it be:

 

msubstance = C% / msubstance + m solvent x100%?

[Cap'n Refsmmat]

You've got an m_substance term on both sides, so you can't really solve for it.

[Chemist98]

Sorry my mistake:)

 

Is it

 

 

msubstance = C% / msolution x100%?

[thedarkshade]

It's got to be like this (IMO):

 

[math]C \% =\frac{m_s}{m_s + m_S} \times 100[/math]

 

multiply with the part under the fraction and you get"

 

[math]C \% \times m_s + C\% \times m_S = m_s \times 100[/math]

 

then move m-substances in one side and the others in the other side:

 

[math]C \%\times m_s - m_s \times 100 = -C\%\times m_S[/math]

 

factorize:

 

[math]m_s(C \% - 100) = m_S[/math]

 

divide with what you got next to m-substance and finally:

 

[math]m_s=\frac{m_S}{C \% - 100}[/math]

 

s = substance

S=solvent

[iNow]

Did you mean this?

 

EDIT:

Deleted: TDS corrected the latex coding in his post.

[thedarkshade]

thanks iNow, I just couldn't figure it out.... tooo fast:D:D .. but there's c-100 not c+100

[iNow]

thanks iNow, I just couldn't figure it out.... tooo fast:D:D .. but there's c-100 not c+100

 

Beautiful. Your first one is still not rendering properly though... Just fyi. Cheers.