Crystalline vs Monohydrate KCl ?

[RalphLambrecht]

What is the conversion factor between crystalline and monohydrate or anhydrous potassium chloride (KCl)?

 

[Vlad Soare]

The ratio between monohydrate and anhydrous would be 1.2416.
However, I'm not sure there is such a thing as KCl monohydrate. I may be wrong about this, but I have a hunch that potassium chloride doesn't form hydrates.

 

[jochen]

Hello Ralph,
this is correct, KCl does not form hydrates. It crystallizes in anhydrous form like NaCl.

 

[RalphLambrecht]

Hello Ralph,
this is correct, KCl does not form hydrates. It crystallizes in anhydrous form like NaCl.

My mistake, however, KCl is hygroscopic. Any way to account for that, or just drying it beforehand as a normal modus operandi?

 

[Gerald C Koch]

Both sodium and potassium chlorides are slightly hygroscopic. Just enough to make them clump in humid weather. Older people will remember the Morton salt motto, "When it rains it pours." Morton used a chemical to prevent clumping. The amount of water absorbed is insignificant for photochemistry calculations.

 

[RalphLambrecht]

Both sodium and potassium chlorides are slightly hygroscopic. Just enough to make them clump in humid weather. Older people will remember the Morton salt motto, "When it rains it pours." Morton used a chemical to prevent clumping. The amount of water absorbed is insignificant for photochemistry calculations.

Gerald

Thanks for the info. You are right. I just found out the hard way. I dried 50 g of KCl in an oven at 80C for 3 hours, hoping to see a measurable weight loss: nothing, not a single gram!