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 20.00 mL of a 2.80 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 10.00 mL of the second solution to a 100.0 mL volumetric flask and adds enough water to dilute to the mark. Calculate the concentration of the Cu2 (aq) solution in the 100.0 mL volumetric flask.

A chemist needs to create a series of standard Cu (aq) solutions for an absorbance experiment. For the first standard, he uses a pipet to transfer 20.00 mL of a 2.80 M Cu(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 10.00 mL of the second solution to a 100.0 mL volumetric flask and adds enough water to dilute to the mark. Calculate the concentration of the Cu*(aq) solution in the 100.0 mL volumetric flask. Number

Explanation / Answer

Case (i):

20 ml of 2.80 M Cu+2 solution is diluted to 250ml,

accroding to the equation

M1V1 = M2V2

2.8 * 20 = M2 * 250

on solving M2= 0.224M

Case (ii):

10 ml of 0.224M solution is diluted to 100ml,

accroding to the equation

M1V1 = M2V2

0.224 * 10 = M2 * 100

on solving M2 = 0.0224 M.

so the concentration of Cu+2 solution in 100ml volumetric flask = 0.0224M

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