A doctor's order is 0.125g of ampicillin. The liquid suspension on hand contains 250 mg/5.0 mL. How many milliliters of the suspension are required?

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Answer 1 · 2016-07-10T13:06:31

#2.5 mL#

First lets get the units the same for the suspension (in #mg#) and the required amount of ampicillin (in #g#):

#1 g = 1000 mg -> 0.125 g = 125 mg#

For easy calculation and for better understanding of what you are doing, it is best to then calculate how many #mg# is in #1 mL#:

#(250 mg) / (5.0 mL)= (50 mg)/(1 mL)#

So #1 mL# of the solution contains #50 mg# ampicillin.
The doctor asks for #125 mg# of ampicillin which is a volume of:

#(125color(red)(cancel(color(black)(mg)))) / (50 (color(red)cancelcolor(black)(mg))/(mL)) = 2.5 mL#

So the required volume of the solution is #2.5 mL#.