One mole of Potassium Persulfate weighs 270.322 g

One mM will weigh 270.322 g. 10-3 = 0.270g

You must weigh 0.270g of potassium persulfate and complete with 1 liter of distilled water, you will then have a solution of 1mM/L.

Is that clear?

thanks for this information

@Safia Taleb that's true, but i want to make a mixture of my model pollutant solution (methylene blue) and potassium persulfate. And i don't know how to reach 1 mM concentration of potassium persulfate in this mixture...adding potassium persulfate as a neat substance, or i should use a pre-prepared solution and what concentration and volume it should be ?

Juraj Michálek If you want to work with a volume of 100ml of MB (10mg / L), you can add 0.027g of persulfate de potassium (which represents 1 mM/L)

@Safia Taleb thank you! And what about hydrogen peroxide, if I have 30 % w/w solution, how to prepare this mixture with methylene blue to reach 1 mM of h2o2?

Juraj Michálek , Hi,

H2O2 at 30% w / w means: 30g of H2O2 in 100g of water. Since water has a density of 1, the calculation will be easy.

Calculation of the molar concentration of 30g of H2O2 = 30/34 (molar mass) = 0.882 moles.

So you have: 0.882moles in 100g of water or 100ml of water;

Or again: 8.82 moles / 1000ml of water.

And to have 1mM, you have to use the following equation:

C1V1 = C2V2

C1 = 0.882moles, C2 = 10-3moles

V1 = 100g, V2?

Do the calculation, because V2 will be the volume that you will take from the H2O2 solution (30%) to add it to your test.

Safia