Question

a student in lab prepared a cereal sample solution for spectroscopic analysis as described in lab 5, and found the concentration of fe3 in the sample to be 2.50 m. if her sample solution was prepared by diluting 28.0 ml of the original solution to a total volume of 100.0 ml, what is the concentration of the original solution?

Answer 1

9.93M

Step-by-step explanation:

A dilution may be dtetermined from the relationship M1V1 = M2V2, where M and V are the concentration (molar) and V is the volume (liters).

M1V1 = M2V2

V1 = 28.0ml or 0.028L

M2 = 2.50M

V2 = 100.00ml or 0.10L

We want M1, so rearrange the equiation:

M1V1 = M2V2

M1 = (M2V2)/V1

Enter the data:

M1 = (M2V2)/V1

M1 = (2.50M*)(0.1L)/(0.028M) [M is moles/L]

M1 = 8.93M

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M1V1 = M2V2 is telling us that we have the same number of moles on both sides of the equation. M is moles/L. M1V1 is (moles/L)*(Liters) = moles of the solute. That is the amount the is used in the new 100 ml solution that is 2.50 Molar. The volume of M1 solution must contain the same number of moles. Thus M1V1 - M2V2