Question

A student takes a sample of KOH solution and dilutes it to 100.00 mL of water. The student determines that the diluted solution is 0.15 M KOH, but has forgotten to record the volume of the original sample. The concentration of the original solution is 3.817 M. What was the volume of the original sample (in mL)

Answer 1

Let us take a look at the known values, or the " given. " C and D stand for concentrated and diluted in this case -

`M_(C ) = 3.817 M,\\M_(D) = 0.15 M`

Given this, let us say that the " original concentrated volume " is x. If so, the " original diluted volume " is x + 100 -

`V_(C) = x,\\V_(D) = x + 100`

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Using the formula "
`M_(C)( V_(C)) = M_D( V_D)` " solve for x, the volume of the original sample,

Mc( Vc ) = Md( Vd ),

3.817( x ) = 0.15( x + 100 ),

3.817x = 0.15x + 15,

3.667x = 15,

x = ( About ) 4.09

( The volume of the original sample is about 4.09 mL )