Question

* if a patient needs 3.5g of a specific antibiotic, how many milliliters of a 25% (m/v) solution of the antibiotic should be given to the patient?

Answer 1

The concentration in terms of mass/volume gives the mass of the substance present per 100mL of solution. In case of a 25% (m/v) solution, 25g will be present in 100mL of the solution. Mathematically, (m/v)% = (mass of solute in g/volume of solvent in mL)x100. So for a 25% solution containing 3.5g, we get 25% = (3.5g/volume of solution)x100 which gives (25/100) = (3.5/volume) giving volume to be 3.5/0.25 = 14mL. Thus, for delivering a 3.5g anitbiotic in 25% (m/v) solution, 14mL of the antibiotic solution is required.