Stock Solution

Definition

A stock solution is a concentrated solution of a chemical substance that is used as a source to prepare other solutions with lower concentrations. It serves as a starting point for making dilutions or other chemical preparations.

5 Must Know Facts For Your Next Test

1. Stock solutions are often used in chemistry laboratories to prepare working solutions with desired concentrations for experiments and analyses.
2. The concentration of a stock solution is typically much higher than the final concentration required for a specific application.
3. Preparing a stock solution involves dissolving a known amount of a solute in a specific volume of solvent, usually water.
4. Stock solutions can be stored for extended periods, providing a convenient and consistent source of the chemical substance.
5. Diluting a stock solution to a lower concentration is a common technique used to create solutions with the appropriate concentration for a particular experiment or application.

Review Questions

• Explain the purpose of using a stock solution in the context of molarity.
  • In the context of molarity, a stock solution serves as a concentrated source of a chemical substance that can be diluted to prepare solutions with specific molar concentrations. By starting with a stock solution of known concentration, chemists can easily calculate the volumes required to create working solutions with the desired molarity for experiments and analyses. This allows for greater precision and consistency in preparing solutions compared to directly weighing out small amounts of solute.
• Describe the process of diluting a stock solution to a lower concentration.
  • To dilute a stock solution to a lower concentration, the general approach is to use the formula: $C_1 \times V_1 = C_2 \times V_2$, where $C_1$ is the concentration of the stock solution, $V_1$ is the volume of the stock solution, $C_2$ is the desired concentration of the diluted solution, and $V_2$ is the final volume of the diluted solution. By rearranging this formula, the volume of stock solution required to prepare the diluted solution can be calculated. The stock solution is then added to an appropriate volume of solvent, usually water, to reach the desired final volume and concentration.
• Evaluate the advantages of using a stock solution over directly weighing out small amounts of a solute when preparing solutions for experiments involving molarity.
  • Using a stock solution offers several advantages over directly weighing out small amounts of a solute when preparing solutions for experiments involving molarity. Firstly, stock solutions allow for greater precision in concentration, as the initial preparation of the concentrated stock solution can be done more accurately than measuring out small masses of a solute. This improved precision carries over to the diluted solutions, leading to more reliable and reproducible results in experiments. Additionally, stock solutions provide a convenient and consistent source of the chemical substance, eliminating the need to repeatedly weigh out small quantities, which can be time-consuming and prone to errors. Furthermore, stock solutions can be stored for extended periods, ensuring a reliable supply of the required chemical for future experiments, whereas directly weighing out small amounts may be more susceptible to losses or contamination over time.

Related terms

Dilution: The process of reducing the concentration of a solution by adding more solvent, such as water or another suitable liquid.

Molarity: A measure of the concentration of a solution, defined as the number of moles of a solute per liter of solution.

Volumetric Flask: A type of laboratory glassware used to prepare solutions of a known concentration, typically by diluting a stock solution to a specific volume.