Problem 4 - Chemistry for Allied Health

Question

What is the volume percent of a solution prepared by adding enough water to 200. mL of acetone to make a total volume of \(1.60 \mathrm{~L} ?\)

Step-by-Step Solution

Answer

The volume percent of acetone in the solution is 12.5%.

Step 1: Identify Key Terms

The problem asks for the volume percent of a solution. This is the percentage of the solute volume (acetone) in the total solution volume. The given volumes are: 200 mL of acetone and a final total solution volume of 1.60 L.

Step 2: Convert Units

Convert the total solution volume from liters to milliliters to have consistent units with the solute volume. Since 1 L = 1000 mL, the total solution volume is \(1.60 \, \text{L} \times 1000 \, \frac{\text{mL}}{\text{L}} = 1600 \, \text{mL}\).

Step 3: Apply the Volume Percent Formula

Volume percent is calculated using the formula:\[\text{Volume Percent} = \left( \frac{\text{Volume of solute}}{\text{Total volume of solution}} \right) \times 100\%\]Substitute the known values into the formula:\[\text{Volume Percent} = \left( \frac{200 \, \text{mL}}{1600 \, \text{mL}} \right) \times 100\%\]

Step 4: Calculate the Volume Percent

Perform the division and multiplication to find the volume percent:\[\text{Volume Percent} = \left( \frac{200}{1600} \right) \times 100\% = 12.5\%\]

Step 5: Conclude with the Result

The volume percent of acetone in the solution is 12.5%.

Key Concepts

Solution Preparation

When preparing a solution, it's essential to understand what we mean by the terms "solute" and "solvent." The solute is the substance being dissolved. In this exercise, acetone is our solute. The solvent, often a liquid, is what the solute is dissolved in—in this case, water. The goal is to create a homogenous mixture where the solute is evenly distributed throughout the solvent.

The preparation starts by measuring the required amount of acetone, which in our example is 200 mL. Then, water is added until the solution reaches the desired total volume of 1.60 L. It is crucial during solution preparation to carefully combine the solute and solvent to achieve accurate concentrations and ensure consistent results across experiments.

Unit Conversion

Unit conversion is a vital process, especially in scientific calculations where consistency is needed. Here, we're dealing with two different volume units: milliliters (mL) and liters (L).

To convert from liters to milliliters, you need to be aware that 1 L is equivalent to 1000 mL. This conversion is straightforward and involves multiplying the liter value by 1000. In our exercise, we convert 1.60 L to milliliters by calculating:

• 1.60 L \( \times 1000 \) mL/L = 1600 mL

Having the same units allows for precise application in volumetric calculations like finding volume percent.

Volume Percent Formula

Volume percent is a way to express the concentration of a solute in a solution. The formula is:

• Volume Percent = \( \left( \frac{\text{Volume of solute}}{\text{Total volume of solution}} \right) \times 100\% \)

This formula gives us the percentage of the solute's volume relative to the total volume of the solution. For our example, with 200 mL of acetone and a total solution volume of 1600 mL, the volume percent comes out to be:

• Volume Percent = \( \left( \frac{200 \, \text{mL}}{1600 \, \text{mL}} \right) \times 100\% = 12.5\% \)

This result indicates that 12.5% of the solution's volume is acetone.

Acetone

Acetone is a colorless, volatile liquid that is commonly used as an industrial solvent and in chemical laboratories. It is also known for its strong odor and its ability to dissolve many substances. This makes it a crucial reagent in many processes, including organic synthesis and nail polish remover production.

In the context of this exercise, acetone acts as the solute. Its handling must be done with care due to its volatility and flammability. Proper lab practices are essential to ensure safety and accuracy when measuring and mixing acetone with other substances like water to prepare solutions.