The technique of "weighing by difference" is a common and essential procedure in analytical chemistry. Here's a description of the technique and the reasons for using it:
**Description:**
- **Weighing by difference** is a method used to determine the mass of a substance indirectly, often involving the subtraction of initial and final masses.
- In this technique, you typically weigh an empty container (such as a beaker or flask) and record its mass.
- Then, you add a quantity of the substance you want to measure into the container and record the combined mass.
- Afterward, you carefully remove most of the substance from the container, leaving behind a small residue or a known quantity.
- Finally, you re-weigh the container with the remaining substance and record the new mass.
**Reasons for Using Weighing by Difference in Analytical Chemistry:**
1. **Minimizing Errors:** Weighing by difference helps minimize errors associated with transferring substances. It reduces the risk of substance loss during transfer, ensuring that the substance is fully accounted for in the analysis.
2. **Precise Measurement:** This technique allows for precise measurements, especially when dealing with substances that are difficult to transfer accurately, like powders, hygroscopic (moisture-absorbing) materials, or substances that can react with the environment.
3. **Calibration and Taring:** It enables the calibration and taring of the container used for weighing, ensuring that the mass of the container itself is accurately accounted for.
4. **Sample Recovery:** Weighing by difference facilitates sample recovery for further analyses or retesting, as a known quantity of the substance is always left in the container.
5. **Quantitative Analysis:** It is crucial for quantitative analyses in analytical chemistry, where precision and accuracy in measuring the quantity of a substance are essential.
6. **Trace Analysis:** In trace analysis, where very small quantities of substances need to be measured, weighing by difference is particularly valuable as it helps recover even tiny amounts of the sample.
In summary, the use of "weighing by difference" in analytical chemistry is essential for accurate and precise measurements. It helps minimize errors, ensures sample recovery, and allows for more reliable quantitative analyses. Therefore, the statement is **True.**