Currently studying for Pharmacy Technician exam. Stumped ondilution/concentratio

Question

Currently studying for Pharmacy Technician exam. Stumped ondilution/concentration formulas.
Question: The formula for a buffer solution contains 1.24% (w/v) ofboric acid. How many milliliters of a 10% (w/v) boric acid solutionshould be used to obtain the boric acid needed in preparing 1gallon of buffer solution.

Answer: 476 mL. 1 Gallon = 3,840 mL: This is a dilution problem,where IS (initial solution) = 10%, IV (initial volume) =unknown, FS (final solution) = 1.24%, and FV (final volume) =3,840 mL: (10%)(IV) = (1.24%)(3,840), IV= 476 mL.

I did 3840*1.24(.1) and it turned out to 476.16, which is thecorrect equivilant. Did I do this correctly? or what? I can'tfigure out the order in which to do these steps. Any advice?

Like... what to do if I have (IS)(IV) = (FS)(x), I just don't knowthe orders for these at all Do I always isolate X (unknown/desired amount)

Currently studying for Pharmacy Technician exam. Stumped ondilution/concentration formulas.
Question: The formula for a buffer solution contains 1.24% (w/v) ofboric acid. How many milliliters of a 10% (w/v) boric acid solutionshould be used to obtain the boric acid needed in preparing 1gallon of buffer solution.

Answer: 476 mL. 1 Gallon = 3,840 mL: This is a dilution problem,where IS (initial solution) = 10%, IV (initial volume) =unknown, FS (final solution) = 1.24%, and FV (final volume) =3,840 mL: (10%)(IV) = (1.24%)(3,840), IV= 476 mL.

I did 3840*1.24(.1) and it turned out to 476.16, which is thecorrect equivilant. Did I do this correctly? or what? I can'tfigure out the order in which to do these steps. Any advice?

Like... what to do if I have (IS)(IV) = (FS)(x), I just don't knowthe orders for these at all Do I always isolate X (unknown/desired amount)

Explanation / Answer

The best way to do this is the trusty equation that all of usbiochemists use in the lab... you should have learned this in basicChem: CV = CV or (Concentration*Volume)=(Concentration*Volume) Plug and chug and you get your answer.

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