Absorbance of solutions containing Cr3+ ions was studied using a Spectronic 20 s

Question

Absorbance of solutions containing Cr3+ ions was studied using a Spectronic 20 spectrophotometer. Solution that is 0.40 M in Cr3+ ion was used as stock solution (solution 1)..... 1. Absorbance of solutions containing Crs+ ions was studied using aspectronic 20 spectrophotometer. The three standard solutions were prepared by dilution of this stock solution according to the table below: Solution mL of standard solution mL of H20 Final concentration, mol/L 12 Calculate the final concentrations of these three standard solutions and enter your answers next to the question marks in the table. In the space provided below, show the set-up you used to determine the final concentration of standard solution 2.

Explanation / Answer

we know that M1V1= M2V2

where M1= Molartiy of stock solution, V1= Volume of stock solution, M2= Molartiy and V2= Volume of final solution

given M1=0.4, V1= 4ml, V2= 4+4= 8ml, M2= 0.4*4/8=0.2

for V2= 12ml, M2= 0.4*4/16= 0.1

for V2= 4+26= 30ml, M2=0.4*4/30 = 0.053M

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