Help with a pharmaceutical math question!

Sounds like a question for cGMP class.
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Took that 2 years ago.

You’re missing a crucial part. mEq/gram in a product are not always equal. You need to know how many mEq of KCl are in one gram of the primary solution.

Once you have that: the start is pretty simple. Identify your question:

?=g(Kcl)/1000ml now you know where to start the conversion. Take the figure on the bottom.

1000ml/1 times(1Tbs/15ml) (5mEq/1 Tbs)

See, you’re doing a conversion of ml to g of Kcl. Set it up as a cross multiplication problem where you are always taking what’s on top of the previous and putting it onto the bottom of the next. That eliminates the terms as they cancel each other out.

You know something about ml – there are 15 in one Tbs. You know something about Tbs – it needs to contain 5 mEq (Kcl). Here is where you can’t complete the problem. You know nothing about how many mEq (Kcl) are in 1 gram.

If you did know that say there were 30 mEq in one gram, you could finish.
(1000/1)(1Tbs/15 ml)(5mEq/1 Tbs)(1g//30mEq))

Then you simply multiply across: 1000*5/15*30 = 166.66g of Kcl

KCl dissociates completely and forms ions K+ & Cl- with a single valence so “equivalents” are the same as “moles” for this substance.
The molecular weight of KCl is (39.1 + 35.5) = 74.6 grams per mole. (I used ptable.com)

How many moles do you need?
The strength is 5 mEq per 15 ml, which equals 0.333 mmoles / ml.
For a quantity of 1000 ml you need 0.333 moles.

(0.333 mol)*(74.6 g/mol) = 24.8 grams.

Good answer @gasman, but complicated for a basic question. I work with Potassium every day and we have base solutions/dry compounds that vary in mEq per gram. It depends.

I was assuming solid potassium chloride as crystals or powder.

I figured you were basing your answer on a pure state of the potassium. I was basing mine on the basic simplicity of the question probably not requiring going to a mole table, but missing a ratio somewhere of Kcl to filler, which is how you generally work with these drugs.