Question

Suppose you start with a solution of red dye #40 that is 4.7 ✕ 10⁻⁵M. If you do four successive volumetric dilutions pipetting 1.00 mL of solution and diluting with water in a 35.00 mL volumetric flask, what is the molarity of the final dilution?

Answer 1

use dilution formula

M1*V1 = M2*V2

1---> is for stock solution

2---> is for diluted solution

use:

M1*V1 = M2*V2

M2 = (M1*V1)/V2

After 1st dilution:

M2 = (M1*V1)/V2

= (4.7*10^-5 * 1.00) / 35.00

= 1.34*10^-6 M

After 2nd dilution:

M3 = (M2*V2)/V3

= (1.34*10^-6 * 1.00) / 35.00

= 3.84*10^-8 M

After 3rd dilution:

M4 = (M3*V3)/V4

= (3.84*10^-8 * 1.00) / 35.00

= 1.10*10^-9 M

After 4th dilution:

M5 = (M4*V4)/V5

= (1.10*10^-9 * 1.00) / 35.00

= 3.1*10^-11 M

Answer: 3.1*10^-11 M