Question

An unknown aqueous metal analysis yielded a detector response of 0.251. When 1.00 mL of a solution containing 100.0 ppm of the metal was mixed with 99.0 mL of the unknown, the detector signal increased to 0.532. Calculate the concentration of the metal in the unknown solution. Report your answer in ppm.

Answer 1

Solution :-

When the 1 ml of 100 ppm solution is added to 99 ml of unknown then concentration of the known metal in the total solution is calculated as follows

C1V1=C2V2

100 ppm * 1 ml = C2 * 100 ml

100 ppm * 1 ml / 100 ml = C2

1 ppm = C2

Therefore the 1 ppm of metal causes the increase in the signal from 0.251 to 0.532

So the change in the signal is 0.532 – 0.251 = 0.281

Now using this signal value we can find the ppm concentration of the metal in the solution

0.251 * 1 ppm / 0.281 = 0.893 ppm

The volume of unknown used was 99 ml and total volume was 100 ml

Therefore

0.893 ppm * 100 ml / 99 ml = 0.902 ppm

Therefore the metal concentration in the unknown solution is 0.902 ppm