Acetone500mg in 25mlVF.Pipettedout 5ml to25ml and again 5ml to 25ml madeupwithDimethylformamide.whats the Ppm?

Question

I added 500mg of acetone into a25ml volumetric flask and made up with dimethylformamide.then i pipetted out 5ml of it to 25ml and madeup with dmf.again i pipettedout 5ml of the above solution to 25ml and madeup with dmf. i would like to know the Ppm of acetone in the third dilution.

Answer 1

assuming the dilutions to be homogeneous,
in the first dilution, 25 ml of dmf contains 500 mg of acetone.
so 5 ml of it contains 100 mg of acetone.
u mixed it again with 25 ml dmf.so that net vol of the resulting soln = 30 ml

30 ml of this soln contains 100 mg acetone.
=> 5 ml of this soln contains = 100/6 = 16.67 mg acetone.

similarly after the third step 5 ml of the soln contains = 16.67/6= 2.78 mg of acetone.

= 2.78*e-3 * 22400/58 = 1.074 ml acetone.
=>Content of dmf = 28.926 ml
molecular mass of dmf= 73
=> mass of 28.926 ml dmf = 28.926 * 73/22400 gm
= 94.267 mg

94.267 mg of dmf contains 2.78 mg acetone
=> 10^6 mg of dmf contains 2.78*10^6 /94.267 = 29490.70 mg

=> the strenght of the soln is 29490.70 ppm.

Answer 2

Do the calculation , its the same as calculation of gases in the air

Answer 3

In what ???????????