A doctor orders 7mg of compazine, which is used to treat nausea, vertigo, and migraine headaches. If the stock solution is 4.0% (m/v) , how many milliliters are administered to the patient?

Question

Answer must have 1 significant figure.

Answer 1

4.0% (m/v) means 4 g of compazine in 100 mls of solution, or 0.04 g compazine / ml of solution.

Converting this to mg compazine / ml solution we have...

0.04 g / ml x 1000 mg / g = 40 mg compazine / ml solution

7 mg compazine x 1 ml / 40 mg = 0.175 ml compazine = 0.2 mls administered (1 sig. fig.)