"Solute 1"Solute 1, "S1"S1, has a molecular mass of 40.0*g*mol^-140.0⋅g⋅mol−1...what is...?

...what is [S1][S1] if a 4*g4⋅g mass of this material is dissolved in a 200*mL200⋅mL volume of solution?

1 Answer
anor277
Aug 29, 2017

By definition, "concentration"-="amount of stuff"/"volume of solution"concentration≡amount of stuffvolume of solution

Explanation:

And typically, we use "molarity"-="moles of solute"/"volume of solution"molarity≡moles of solutevolume of solution

And thus "concentration of S1"concentration of S1

=((4*g)/(40.0*g*mol^-1))/(200*mLxx10^-3*L*mL^-1)=0.50*mol*L^-1=4⋅g40.0⋅g⋅mol−1200⋅mL×10−3⋅L⋅mL−1=0.50⋅mol⋅L−1

And note the dimensionality of this solution....

We cancel out common terms in the numerator and denominator....

=((4*cancelg)/(40.0*cancelg*mol^-1))/(200*cancel(mL)xx10^-3*L*cancel(mL^-1))=0.5*(1/(mol^-1))/L=0.50*mol*L^-1

Why? Because 1/x^-1=1/(1/x)=x as required................

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