What Is a Working Solution?
A working solution is a chemical solution prepared for immediate use in an experiment, typically by diluting a more concentrated solution called a stock solution. It is the solution at the desired concentration required for a specific analytical procedure, test, or experiment.
Section 2: Stock Solution vs. Working Solution
The key difference lies in concentration and purpose. A stock solution is a highly concentrated, accurately prepared solution that is stored for long-term use. A working solution is a less concentrated version created by taking a small volume of the stock solution and diluting it with a solvent to the final volume and concentration needed for the actual work.
Section 3: A Practical Example
Imagine a lab has a 1.0 M (molar) stock solution of sodium chloride (NaCl). A scientist needs to perform an experiment that requires 100 mL of a 0.1 M NaCl solution. They would prepare a working solution by taking 10 mL of the 1.0 M stock solution and adding 90 mL of deionized water to reach the final volume of 100 mL.
Section 4: Importance in the Lab
Using a stock and working solution method is crucial in a laboratory setting. It saves time, reduces the potential for error when weighing small amounts of a chemical, conserves expensive or hazardous reagents, and ensures consistency across multiple experiments that are performed on different days.