Examples of Preparing Molar Solutions from Solid Solute

Explore practical examples of preparing molar solutions from solid solutes in chemistry.
By Jamie

Understanding Molar Solutions

Molarity is a key concept in chemistry that describes the concentration of a solution. It is defined as the number of moles of solute per liter of solution. Preparing a molar solution from a solid solute involves precise measurements and calculations to ensure the desired concentration is achieved. Below are three practical examples that illustrate this process.

Example 1: Preparing a 1M Sodium Chloride Solution

In laboratory settings, sodium chloride (NaCl) is often used for various experiments, including biological assays and chemical reactions. A 1M sodium chloride solution is a common requirement for many applications.

To prepare this solution, you will need to calculate the mass of NaCl required. The molar mass of NaCl is approximately 58.44 g/mol. For a 1L solution:

  • Calculate the mass of NaCl needed:

    1 mol/L × 58.44 g/mol × 1 L = 58.44 g

  • Procedure:

    1. Weigh out 58.44 grams of NaCl using a balance.
    2. Transfer the NaCl into a 1-liter volumetric flask.
    3. Add distilled water to the flask until the total volume reaches 1 liter.
    4. Mix thoroughly to ensure the salt dissolves completely.

  • Notes: Ensure to label the flask with the concentration and date of preparation. If preparing a different volume, adjust the mass of NaCl accordingly using the formula: mass = molarity × molar mass × volume (in liters).

Example 2: Creating a 0.5M Acetic Acid Solution

Acetic acid is widely used in both industrial applications and laboratory settings. Preparing a 0.5M solution is useful for various titration experiments.

The molar mass of acetic acid (CH₃COOH) is approximately 60.05 g/mol. To prepare 500 mL of a 0.5M solution:

  • Calculate the mass of acetic acid needed:

    0.5 mol/L × 60.05 g/mol × 0.5 L = 15.0125 g

  • Procedure:

    1. Weigh out 15.0125 grams of acetic acid.
    2. Place the acetic acid into a 500 mL volumetric flask.
    3. Add distilled water carefully to the flask until the total volume reaches 500 mL.
    4. Stir the solution to ensure complete mixing.

  • Notes: Use a fume hood when handling acetic acid, as it can release vapors. Adjust the mass if preparing a different volume, applying the same formula as in the previous example.

Example 3: Synthesizing a 0.1M Potassium Nitrate Solution

Potassium nitrate (KNO₃) finds applications in fertilizers and as a food preservative. Preparing a 0.1M solution is often required for experiments involving plant growth or chemical synthesis.

The molar mass of potassium nitrate is approximately 101.10 g/mol. To create 250 mL of a 0.1M solution:

  • Calculate the mass of potassium nitrate needed:

    0.1 mol/L × 101.10 g/mol × 0.25 L = 2.5275 g

  • Procedure:

    1. Weigh out 2.5275 grams of potassium nitrate.
    2. Add the potassium nitrate into a 250 mL volumetric flask.
    3. Fill the flask with distilled water until the total volume reaches 250 mL.
    4. Mix well to ensure complete dissolution.

  • Notes: Potassium nitrate is hygroscopic, so store it in a dry environment. Always remember to scale the mass according to the desired final volume of the solution.

These examples demonstrate the straightforward process of preparing molar solutions from solid solutes. By following these steps and adjusting the calculations according to your needs, you can effectively create solutions for various applications in chemistry.