[xoedusk]

Greetings all. I'm making a Mac program that can be used to help keepers of aquatic plants mix their own fertilizers. I have been getting my data from the following website, which is used by many fishkeepers to calculate solutions.

http://www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm

Check out potassium nitrate. The listed density at the bottom of the page is 5.6 g/tsp.

Yet when I look online for other resources, I find that they list the density as about 2.1 g/cm^3 = 10 g/tsp.

Any ideas on this contradiction?

BTY, here is a screen shot of the program.

[Yggdrasil]

Perhaps its the difference between having a giant, solid crystal of KNO3 or having loose grains of KNO3.

[xoedusk]

Hmm this would make sense. So when Wiki or other sites list the density of a substance (say NaCl), the density is of a solid chunk of crystal? and not the more powdery form?

[Borek]

IIRC density of powder may depend on the way it was prepared.

My handbook (in Polish) says 2.1.

Google for knovel international critical tables. I think once you register you can downlad parts of the book for free for several days.