[saqibjahtemuri]

I have KCl chemical sacks for oil and gas wells stimulation. Sacks have written on them 62% K2O. Why is conc of K2O mentioned on top of sack when i am buying KCl from vendor. Is there any symbolic relationship between K2O and KCl purity.
What might be the reason for this. The chemical is 98% pure KCl.

[Borek]

There was a thread some time ago about expressing concentrations, I can't find it right now.

In short: it tells you how much K₂O would contain equivalent amount of potassium.

And 62% is more or less theoretical equivalent (63.2% being the exact number).

[Arkcon]

What the bag's label is saying is, the content of KCl in the bags is 62%, if it were converted to K₂O.  Like Borek: said, this is how, historically, the material was assayed in the past, and we just continue the convention.  Often this is done for fertilizers -- KCl, KNO₃, NaK-molybdate can all be expressed as amount of K₂O.  That way you know how much potassium you're adding, even as you add other ions.

[AWK]

This can be aesily calculated
2KCl is equivalent to K₂O

[saqibjahtemuri]

Why is K2O taken as standard, although it is too  much reactive and is rarely found as compared to KCl. For comparison we generally used a substance which is either unique in its properties or is abundant.

[Borek]

Why is K2O taken as standard

Because that's the way it is.

There is no special logic here, someone started it this way many years ago (perhaps even back in 19th century) and it stuck.