Cobalt nitrate is highly soluble in water. Make 100 ml of measured stock solution and make desired concentrati by dilution process.

Dear Danika Putri ,

the challenge to calculate here the amount of Co(NO3)2 for a 25ml solution of given concentration is, that the volumes of the two components (here Co(NO3)2 and water) do not simply add, but merge in an unknown way.

So I suggest to first produce the 5, 10, and 20 wt% solutions irrespective of the 25ml goal and then pick up the 25 ml of these solution(s) e.g. by a calibrated pipette.

The solutions may be mixed for example by

a) 5g of Co(NO3)2 and 95g (or ml) of water for a 5 wt% solution, and

b) 10g of Co(NO3)2 and 90g (or ml) of water for a 10 wt% solution, as well as

c) 20g of Co(NO3)2 and 80g (or ml) of water for a 20 wt% solution

good luck and best regards

G.M.

Hi Danika,

You may use the web tool to calculate

https://www.alfa-chemistry.com/mass-molarity-calculator.htm