Chemistry Question - The Planted Tank Forum
Old 09-20-2005, 09:54 PM Thread Starter
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Chemistry Question

Hi guys,

If I have a concentrated solution, and the directions are to mix 2 ml into 1 gallon and the result would be 2.4% potassium, what does that mean?
sarahbobarah is offline

Old 09-20-2005, 10:33 PM
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It means you've diluted the concentrated solution into a 2.4% solution. C1V1=C2V2 where C = concentration V = volume

Plug in the numbers and work the algebra

Re-boot!
Old 09-20-2005, 10:35 PM
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Beat me to it!

Just make sure all your units are the same (first convert the gallon into mL).

Ken T.
cousinkenni is offline

Old 09-20-2005, 10:41 PM
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Actually that calculation isn't even possible in my opinion.

Ken T.
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Old 09-20-2005, 10:42 PM Thread Starter
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Yes, but how does that translate to ppm?

My degree was in Literature, and I've not inherited my parents' affinity for math (or logic)
sarahbobarah is offline
Old 09-20-2005, 10:49 PM
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unless the original post is incorrect and 2ml into a gal give 2.4ppm then there is no possible way to calculate anything.

If what was posted was correct you would have to have a solution of potassium that is over 4000% (not possible). We also need to know what compound the potassium was coming from and original powder mass (dry) or molarity(liquid) to calculate ppm.

Ken T.
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Old 09-20-2005, 10:55 PM Thread Starter
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Darnit. That's all it says on the bottle.

Ok, I guess what I'm also confused about is the NPK on the label. If a solution has 5-0-2 as its NPK, then does that mean that the solution, no matter how you measure it, will be 5% N, 0% P, and 2% K?
sarahbobarah is offline
Old 09-20-2005, 11:14 PM
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Have a brand name?

Regards,
Tom Barr

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Old 09-20-2005, 11:45 PM
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Quote:
Originally Posted by sarahbobarah
Darnit. That's all it says on the bottle.

Ok, I guess what I'm also confused about is the NPK on the label. If a solution has 5-0-2 as its NPK, then does that mean that the solution, no matter how you measure it, will be 5% N, 0% P, and 2% K?

That is correct.
Rex Grigg is offline
Old 09-21-2005, 01:31 AM
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Quote:
Originally Posted by sarahbobarah
Darnit. That's all it says on the bottle.

Ok, I guess what I'm also confused about is the NPK on the label. If a solution has 5-0-2 as its NPK, then does that mean that the solution, no matter how you measure it, will be 5% N, 0% P, and 2% K?
It means 5% N2O5 (IIRC) equivalent, 2% K2O equivalent. This is the standard method for measuring/comparing fertilizers. Unfortunately, it is not that useful for aquaria - since we want to know ppm.

2% K2O = 2g K2O in 100ml solution. 2g K2O * 78g K/94g K2O = 1.66g K per 100ml solution (or 16.6mg K per 1ml solution)

Kevin

Kevin

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KevinC is offline
Old 09-21-2005, 02:10 AM
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It's not possible to start at a 2% concentration in your solution and to dillute it and end up with 2.4%.
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