### (type 3) Calculate mg per volume from mEq per volume

5. mEq and mOsmol 5.1) mEq 5.1.1) mEq - General

5.1.1.1) mEq from weight/volume Normal 1

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If penicillin V potassium solution is expressed as 5.15 mEq/L, then how many milligram of penicillin V potassium will be present in each 100 mL of the solution? Round your answer to the nearest tenth. The molecular weight of penicillin V potassium is 388 g/mol.

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lb equals 200 mg/100mL kg

The molecular weight of penicillin V potassium = 388.
Valence or charge = 1.
Therefore, we can write: 388 mg = 1 mEq.
Since the question needs mg/100 mL as the final unit, we keep 388 mg in the starting numerator. So, 1 mEq will be the denominator.
Also, the solution contains 5.15 mEq per L; therefore, the mEq is used as the numerator for the second fraction, in order to cancel out. The dimensional analysis will be like this:

(388 \quad mg)/(1 \quad mEq) × (5.15 \quad mEq)/(1 \quad L) × (1 \quad L)/(1000 \quad mL) × (100 \quad mL)/(100 \quad mL)
 = 200\quad (mg)/(100 \quad mL) Ans.