If you have 100 mL of a 30% ethanol solution, what is the volume of ethanol in that solution?

To determine the volume of ethanol in a 30% ethanol solution, it is important to understand what the percentage concentration represents. A 30% ethanol solution means that 30% of the total volume of the solution is ethanol.

In this case, we have a total volume of 100 mL of the solution. To find out the volume of ethanol, you can calculate 30% of 100 mL. This can be done using the formula:

[

\text{Volume of ethanol} = \text{Total volume} \times \left(\frac{\text{Percentage}}{100}\right)

]

Substituting the values gives us:

[

\text{Volume of ethanol} = 100 , \text{mL} \times \left(\frac{30}{100}\right) = 30 , \text{mL}

]

Thus, the volume of ethanol in the solution is 30 mL. This is why the answer is correct. It effectively translates the percentage into a tangible volume, which is crucial for understanding solution concentrations in analytical chemistry. The application of this simple calculation also illustrates how concentration and volume relate to each other, fostering a deeper understanding of solution chemistry.