Some people have begun to formulate their own window-cleaning solutions using commonly available household chemicals. One formulation calls for mixing vinegar (dilute acetic acid, \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) ) with water and a small amount of detergent. A commonly used recipe contains \(14.3 \mathrm{~g}\) of acetic acid mixed with \(525.0 \mathrm{~g}\) of water and \(1.3 \mathrm{~g}\) of detergent. This recipe makes a total of \(540.0 \mathrm{~mL}\) of solution. (a) What is the mass percent of acetic acid in the window cleaner? (b) What is the molarity of acetic acid in the window cleaner?

Mass percent is a way to express the concentration of a component in a mixture. It tells us the mass of a solute (in this case, acetic acid) compared to the total mass of the solution, as a percentage. To calculate the mass percent, you use the formula:
\text{Mass percent} = \(\frac{\text{mass of solute}}{\text{total mass of solution}} \times 100\text{\text{%}}\).
In our example, the mass of acetic acid is 14.3 g, and the total mass of the solution is the sum of all its parts: 14.3 g (acetic acid) + 525.0 g (water) + 1.3 g (detergent) = 540.6 g.
When we plug these values into the formula, we get: \text{Mass percent} = \(\frac{14.3}{540.6} \times 100\) = 2.65%.
This means acetic acid makes up 2.65% of the window cleaning solution by mass.

Molarity is another way to express concentration, but it focuses on the number of moles of a solute in a given volume of solution. The formula for molarity is:
\text{Molarity} = \(\frac{\text{moles of solute}}{\text{liters of solution}}\).
First, you need to convert the mass of the solute (acetic acid) into moles. Acetic acid has a molar mass of 60.05 g/mol. Using the given mass of 14.3 g, you can find the moles of acetic acid: \text{Moles of acetic acid} = \(\frac{14.3 \text{ g}}{60.05 \text{ g/mol}}\) = 0.238 mol.
Then, convert the volume of the solution from mL to L: 540.0 mL = 0.540 L.
Finally, plug these values into the molarity formula: \text{Molarity} = \(\frac{0.238 \text{ mol}}{0.540 \text{ L}}\), which gives 0.441 M. This means the molarity of acetic acid in the solution is 0.441 M.

Acetic acid, with the chemical formula HC₂H₃O₂, is a key component of vinegar. It is the ingredient that gives vinegar its sour taste and strong smell.
In the context of solution chemistry, acetic acid is often diluted in water to make household cleaning solutions, including window cleaners.
When dealing with acetic acid, you might come across terms like 'glacial acetic acid,' which is undiluted and quite concentrated, compared to the diluted form used in vinegar.
Understanding the properties of acetic acid, including its molar mass (60.05 g/mol), is crucial when calculating concentrations in solutions. For instance, knowing the chemical reactions it undergoes can help explain why it is effective in cleaning applications.

Solution chemistry involves studying how different substances dissolve and interact in a solution. There are many key terms and concepts:
• **Solute**: The substance that is dissolved in a solvent (e.g., acetic acid in water).
• **Solvent**: The substance that dissolves the solute (e.g., water in our window-cleaning solution).
• **Mass percent and molarity**: Two ways to measure and describe concentrations of solutions.
Understanding these basics is essential for tasks like preparing solutions in precise concentrations. When making homemade cleaning solutions, knowing how to calculate mass percent and molarity ensures they are effective and safe for use.
By grasping these concepts, students can accurately follow recipes and even create their own solutions tailored to specific needs, while ensuring they use the correct proportions of substances.