An antibiotic is sold in 4.0 mL ampoules that contain 60.0 mg of drug (60.0 mg/ 4.0 mL). How many milliliters of the antibiotic should be withdrawn from the ampoule if 20 mg are to be administered to a patient?Use correct number of sig figs
0.75ml?
No, and you know that is wrong because 60mg/4.0 mL = 15 mg/mL and
15 mg/mL x 0.75 mL is not 20 mg.
(60 mg/4.0 mL) x ?mL = 20 mg.
?mL = 20 x 4/60 = ?
You are allowed 2 s.f.
1.3 ml
right
To answer this question, we need to calculate the volume of the antibiotic that contains 20 mg of the drug.
Given:
- Each ampoule contains 60.0 mg of the drug
- Each ampoule has a volume of 4.0 mL
To find the volume containing 20 mg of the drug, we can set up a proportion using the ratio of drug to volume:
(60.0 mg / 4.0 mL) = (20 mg / x mL)
To solve for x (the volume containing 20 mg of the drug), we can cross-multiply and solve for x:
60.0 mg * x mL = 4.0 mL * 20 mg
x = (4.0 mL * 20 mg) / 60.0 mg
x = (80 mg * mL) / 60 mg
Simplifying, we find that:
x = 1.33 mL
Now, considering the correct number of significant figures, since the given values have three significant figures, we need to round the answer to three significant figures as well.
Therefore, the correct answer with the appropriate number of significant figures is:
x = 1.33 mL
So, the correct volume of the antibiotic that should be withdrawn from the ampoule to administer 20 mg to the patient is 1.33 mL, not 0.75 mL as you suggested.