Preparing a Solution
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
Topic Summary & Highlights
and Help Videos
Core Concept
Preparing a solution in chemistry involves dissolving a specific amount of solute in a solvent to achieve a desired concentration (usually expressed in molarity, M). Focus on the steps involved in the process and common mistakes to avoid in the process.
Practice Tips/ Common Mistakes to Avoid
Adding Solute After Final Volume is Reached: Always add solute before reaching the final volume to ensure the concentration is accurate.
Improper Meniscus Reading: Ensure the bottom of the meniscus is level with the calibration line to avoid incorrect volume measurements.
Incomplete Mixing: If the solution is not mixed thoroughly, the concentration may be inconsistent throughout the solution.
Core Concept
Preparing a solution of a specific concentration involves dissolving a known amount of solute in a given volume of solvent. Proper technique and attention to detail ensure that the solution concentration is accurate.
Here are the steps on how to prepare (make) a solution:
Pre-Step
Calculate the amount of solute needed: Use the desired concentration and the volume of solution you want to prepare to calculate the amount of solute (substance being dissolved) required. This calculation involves using the formula:
From concentrated solution: Amount of solute (in grams or moles) = Concentration x Volume of solution
From solid solute: Find mass needed
Weigh or measure the solute: Accurately measure the calculated amount of solute using a balance or other measuring instrument. Use proper lab techniques to ensure precision.
Transfer the solute to a container: Transfer the measured solute to an appropriate container, such as a beaker or flask. If necessary, use a funnel to avoid spillage.
Add the solvent: Add the solvent (usually water) to the container containing the solute. Use a graduated cylinder or pipette to measure the required volume accurately. Add the solvent slowly while stirring or swirling the container to aid in the dissolution of the solute.
Dissolve the solute: Stir or agitate the mixture gently to ensure the solute dissolves completely in the solvent. Use a glass stirring rod or magnetic stirrer, if available.
Transfer to a final container: Once the solute has dissolved completely, transfer the solution to the final container, such as a volumetric flask or storage bottle. Rinse the container and any equipment used to ensure all the solution is transferred.
Common Mistakes to Avoid:
Over-Dilution:
Adding solvent beyond the desired final volume reduces concentration.
Incomplete Dissolution:
Ensure the solute dissolves fully before making up the final volume to avoid concentration errors.
Using Incorrect Units:
Always use liters for volume when calculating molarity and grams for solute mass.
Contamination:
Use clean equipment to avoid contaminating the solution.
Adding Solute After Solvent:
Always add the solute first and dilute with solvent to ensure precise concentration.