Calculating Grams of Ethanol in an Ethyl Alcohol Solution

Understanding Ethanol Concentration and Density

When working with ethyl alcohol solutions, it is often necessary to calculate the exact amount of ethanol in the solution. This is particularly useful in scientific and industrial applications where precise measurements are critical. This article will guide you through the process of determining the grams of ethanol in a 70% (w/w) ethyl alcohol solution with a known volume and density.

Given Data and Assumptions

We are given the following parameters:

Volume of the solution: 2.0 L Concentration: 70 w/w (weight/weight) Density of the solution: 0.791 g/mL

Let's break down the calculation step-by-step.

Step 1: Calculate the Mass of the Solution

To find the mass of the solution, we use the formula:

Mass Volume × Density

Volume 2.0 L 2000 mL (1 L 1000 mL) Density 0.791 g/mL

Therefore:

Mass of solution 2000 mL × 0.791 g/mL 1582.0 g

Step 2: Calculate the Mass of Ethanol

The concentration of the solution is given as 70% (w/w), meaning 70% of the mass of the solution is ethanol. To find the mass of ethanol, we use the following formula:

Mass of solute (Concentration%) × Mass of solution

Concentration 70%, Mass of solution 1582.0 g

Therefore:

Mass of ethanol 70% × 1582.0 g 0.70 × 1582.0 g 1107.4 g

So, 1107.4 grams of the solution is ethanol.

Conclusion

In summary, if you have 2.0 liters of a 70% (w/w) ethyl alcohol solution with a density of 0.791 g/mL, the amount of ethanol in the solution is 1107.4 grams. This calculation can be applied to other concentrations and volumes by adjusting the given values accordingly.

Keywords

ethanol grams density calculation solution concentration