1. In a 100 mL volumetric flask, 30.0 mL of 0.150 M NaOH is combined with 25.0 mL of 0.125 M red dye solution and brought up to volume using DI water. Calculate the final concentrations of both the NaOH and the red dye. Show all your calculations.

Question

Chemistry

Henry Krause

30 May, 18:27

1. In a 100 mL volumetric flask, 30.0 mL of 0.150 M NaOH is combined with 25.0 mL of 0.125 M red dye solution and brought up to volume using DI water. Calculate the final concentrations of both the NaOH and the red dye. Show all your calculations.

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Answers (1)

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Angelo Boyd · Answer 1

[NaOH] = 0.045 M

[red dye] = 0.031 M

Explanation:

The NaOH and the red dye will not react between them, so, the process that it's occurring is only a dilution. The final volume of the solution will be the volume of the flask, which is 100 mL.

The number of moles (n) of each substance will not vary, and it's calculated by the multiplication of the concentration (C) by the volume (V). If 1 is the initial solution, and 2 the diluted:

n1 = n2

C1*V1 = C2*V2

For NaOH:

C1 = 0.150 M

V1 = 30.0 mL

V2 = 100 mL

0.150*30 = C2*100

100C2 = 4.5

C2 = 0.045 M

For the red dye:

C1 = 0.125 M

V1 = 25.0 mL

V2 = 100 mL

0.125*25 = C2*100

100C2 = 3.125

C2 = 0.031 M