ammonium hydroxide Percent to normality conversion

[KKAK]

Hi all,
I was trying to make a 0.3N ammonium hydroxide solution from the stock (Fluka). The label on the stock says it is "10% assay in water", what does it mean? Is it 10% v/v? How should I prepare a 1ml 0.3N ammonium hydroxide? I don't quite understand the solute mass equivalent concept of normality.

Thank you

[Gokul43201]

You could call the company and find out how they specify the assay. For solid solutes, the assay is typically w/w and for liquid solutes it is often v/v. In this case though, the solute is a highly soluble gas (NH3), and it might turn out that they are using a molar % instead.

As for converting molarity to normality, you need to understand the concept of an equivalent weight. The primary question to ask yourself is this: If I dissociate 1 formula unit of the compound, how many electrons are transfered between the cationic part and the anionic part?

To be more rigorous, the normality is a function of the reaction that the compound is involved in. For some compounds, the normality for a given molarity can be different under different situations. In the case of NH4OH though, this is unlikely.

[chemisttree]

Commercially available solutions are almost always listed as w/v. I've never seen it expressed otherwise. Thus 37.5% hydrochloric acid would be 37.5 grams HCL in 100 mL of solution. It makes the calculations easiest that way since you can weigh an aliquot of the stock solution and dilute to a known volume to obtain your solution.

[Gokul43201]

Commercially available solutions are almost always listed as w/v. I've never seen it expressed otherwise. My bad! :redface:

I haven't needed to know the exact concentration of any of the reagents I've used in a long time. The three concentrations I commonly use are: really dilute, straight from the bottle and on the rocks, please! :biggrin:

[Riogho]

0.3N?

Isn't that M?

>.<