Question

you will make four dilutions of your 0.10M cobalt(II) nitrate solution. The lowest concentration that works in the spectrometer is 0.010M cobalt(II) nitrate. Write out the calculations for four dilutions, starting from 0.10M, with the lowest being 0.010M or greater.

Answer 1

Followings are the suitable lowest concentrations

0.08M, 0.06M , 0.04M and 0.02M

the formula for dilution is

C1 × V1 = C2 × V2

where,

C1 = initial concentration

V1 = Initial volume

C2 = Final concentration

V2 = Final Volume

Let us prepare each 100ml of the above standard solutions

i)100ml of 0.08M atd solution

V1 = C2 × V2/C1

= 0.08M × 100ml / 0.10M

= 80ml

So, take 80ml from stock solution (0.10M) and trensfer it into 100ml Volumetric flask and make up to the mark

ii) 100ml of 0.06M std solution

V1 = 0.06M ×100ml/0.1M

= 60ml

take 60ml from 0.1M stock solution , and make up it for 100 ml

iii) 100ml of 0.04M std solution

V1 = 0.04M × 100ml /0.1M = 40ml

take 40ml from 0.1M stock solution , and make up it for 100ml

iv) 100ml of 0.02M std solution

V1 = 0.02M × 100ml /0.1M = 20ml

take 20ml from 0.1M stock solution and make up it for 100ml