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?

1 Answer
Jul 10, 2016

2.5 mL

Explanation:

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.