Beer\'s Law, Hands-On Labs, Version 42-0140-00-03 I have 50.0mL of distilled wat

Question

Beer's Law, Hands-On Labs, Version 42-0140-00-03
I have 50.0mL of distilled water and added 10 drops (.5mL) of blue dye which has a molarity of 0.026M; we'll call this solution standard blue dye. The first picture shows how the M2 is calculated. In picture 2 you will see I have 11 test tubes (all test tubes will have only 5mL of solution in them) starting with B which has 5mL of standard blue dye and 0 mL of distilled water. Solution will be added to each test tube in varying intervals as you will see in the table. The manual wants us to use the equation on picture 1 (M1V1=M2V2) to get the final concentration. I am having a problem figuring this out, can you give me step by step help. I know how to use the equation but I don't know where to input the values. Thanks for your help!

Explanation / Answer

M1V1 = M2V1 is used to find the concentration of final solution.

For tube B, volume of standard blue dye = 5 mL

Total volume in test tube = 5.0 mL

Concentration of blue dye = 2.57 E-4 M

Concentration of blue dye in tube 1:

Volume of stock solution with molarity 2.57 E-4 M is 5.0 mL ,

From this stock solution we use 0.5 mL of this stock solution and dilute to 5.0 mL in tube1.

There fore,

M1= 2.57 E-4 M , V1 = 4.5 mL , V2 = 5.0 mL ( final volume)

We have to find M2 ( final molarity)

Lets use M1V1 = M2V2

M2=M1V1/V2 = 2.57E-4 M x 4.5 mL / 5.0 mL = 0.0002313 M = 2.3 E-4 M

Now for next dilution , in tube level 2 ,

We have 4.0 mL of stock solution and so its M1= 2.57 E-4   , V1 =4.0 mL , V2 = 5.0 mL

M2 = 4.0 mL x 2.57 E-4 M / 5.0 mL = 2.06 E-4 M

Level 3

M2 = 3.5 mL x 2.57 E-4 M / 5.0 mL = 1.80 E – 4 M

Level 4

M2 = 3.0 mL x 2.57 E-4 M / 5.0 mL = 0.000154 E -4 M

Level 5

M2 = 2.5 mL x 2.57 E-4 M / 5.0 mL = 1.23 E-4 M

Level 6

M2 = 2.0 mL x 2.57 E-4 M / 5.0 mL = 1.03 E -4 M

Level 7

M2 = 1.5 mL x 2.57 E-4 M / 5.0 mL = 7.71 E-5 M

Level 8

M2 = 1.0 mL x 2.57 E-4 M / 5.0 mL

= 5.14 E -5 M

Level 9

M2 = 0.5 mL x 2.57 E-4 M / 5.0 mL = 2.57 E-5 M

In level 10 there is no presence of dye so Molarity of dye would be zero.

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