How would you prepare each of the following solutions? (b) 100 mL of an aqueous solution whose K+ concentration is 0.075 M

Verified step by step guidance

1. Determine the moles of K+ needed: Use the formula \( \text{moles} = \text{molarity} \times \text{volume} \). Convert the volume from mL to L by dividing by 1000.
2. Calculate the moles of K+ required: Multiply the molarity (0.075 M) by the volume in liters (0.1 L) to find the moles of K+.
3. Select a potassium salt: Choose a soluble potassium salt, such as potassium chloride (KCl), to provide the K+ ions.
4. Calculate the mass of the potassium salt needed: Use the molar mass of the chosen salt (e.g., KCl) to convert moles of K+ to grams of the salt.
5. Dissolve the calculated mass of the potassium salt in water: Add the salt to a volumetric flask and add water until the total volume reaches 100 mL.

Key Concepts

Molarity

Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. It is a crucial concept in preparing solutions, as it allows chemists to quantify how much solute is dissolved in a given volume of solvent. In this case, a 0.075 M solution means there are 0.075 moles of potassium ions (K+) in every liter of the solution.

Dilution

Dilution is the process of reducing the concentration of a solute in a solution, typically by adding more solvent. When preparing a specific molarity, understanding how to dilute a more concentrated stock solution to achieve the desired concentration is essential. The dilution formula, C1V1 = C2V2, helps calculate the volumes needed to achieve the target concentration.

Preparation of Aqueous Solutions

Preparing an aqueous solution involves dissolving a solute in water to create a homogeneous mixture. For the given problem, one would need to accurately measure the required amount of potassium salt (like KCl) that provides the desired K+ concentration when dissolved in water. This process requires precision in measuring both the solute and the final volume of the solution.