Question

lidocaine, a widely used local anesthetic, is available as a 1.0%(w/v) solution for injection.
calculate the volume of this solution that contains 70. mg of lidocaine. be sure your answer has a unit symbol and is rounded to the correct number of significant digits.

Explanation:

Step1: Convert percentage to ratio

A \(1.0\%(w/v)\) solution means \(1.0\space g\) of lidocaine per \(100\space mL\) of solution. Since \(1\space g = 1000\space mg\), this is equivalent to \(1000\space mg\) per \(100\space mL\), or a ratio of \(\frac{1000\space mg}{100\space mL}=10\space mg/mL\).

Step2: Calculate the volume

We know the concentration \(C = 10\space mg/mL\) and the mass \(m=70\space mg\). Using the formula \(V=\frac{m}{C}\), we substitute the values: \(V=\frac{70\space mg}{10\space mg/mL}\).

Answer:

\(7.0\space mL\)