Question

Lidocaine, a widely used local anesthetic, it’s available as a 2.0% (w/v) solution for injection. Calculate the volume of the solution that contains 60 mg of lidocaine. Be sure your answer has a unit symbol and is rounded to the correct number of significant digits.

Answer 1

Givens.

• Lidocaine is available as a 2.0% (w/v) solution.

,

• The mass of solute is 60. mg of lidocaine.

To find the volume of this solution, we use the following equation.

$(\frac{w}{v})=\frac{Mass\text{ of solute}}{Volume\text{ of solution}}$

Use the given magnitudes and solve for volume.

$\begin{gathered} 0.02=\frac{60mg}{V} \\ V=\frac{60mg}{0.02} \end{gathered}$

But, we need to use grams.

$V=\frac{0.060g}{0.02}=3$

Therefore, the volume of this solution is 3.0 mL.