A chemist needs to create a series of standard Cu2 (aq) solutions for an absorba

Question

A chemist needs to create a series of standard Cu2 (aq) solutions for an absorbance experiment. For the first standard, he uses a pipet to transfer 10.00 mL of a 2.49 M Cu2 (aq) stock solution to a 250.0 mL volumetric flask and adds enough water to dilute to the mark. He then uses a second pipet to transfer 20.00 mL of the second solution to a 50.00 mL volumetric flask and adds enough water to dilute to the mark. Calculate the concentration of the Cu2 (aq) solution in the 50.00 mL volumetric flask.

Explanation / Answer

Concentration of Cu^2+ in the first 250mL volummetric flask.

M = 10 mL * 2.49 M/250 mL = 0.0996 M

Concentration after diluting for the second time :

M1V1 = M2V2

where M1 and M2 is the concentration of the solution before and after the dilution. V1 and V2 is the initial and final volume of the solution.

M2 = M1V1/V2 = 0.0996 M * 20mL/50 mL = 0.039 M

Concentration of Cu^2+ ion in 50 mL volummetric flask = 0.039 M

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