1. Essence of gravimetric ( weighting ) analysis, its features.
2. Methods of phase separation elements.
3. Requirements to precipitates in quantitative analysis.
4. Solubility product , its use in gravimetry.
Essence of gravimetric ( weighting ) analysis, its features.
The most common method of weighting analysis consist in transfer determing component in the sediment, separating it from the solution, transfer in stoichiometric form and weighing. For the mass of sediment calculate the mass of the component, which determined:
X + R ↔ P ↓
Weighting analysis – one of the most well known and well-studied methods of analysis. With it help is set the chemical composition of most substances, and atomic weights of elements. Its positive side – simple techniques and equipment availability . However, the weighting method has several disadvantages , including the principal – the high cost of labor and time, and the difficulty in determining small quantities of substances . Therefore, nowadays in practice of quantitative analysis weighting method is used relatively rarely, and researchers are trying to replace it with other methods. However weighting method is used to determine the large number of components , for example , SiO2 and sulfate in the so-called silicate analysis. The method of weighting analysis often set purity of initial preparations, and concentration of solutions for other methods of analysis. In technical analysis very handy gravimetric method to determine the ash content and moisture content of materials. Learning theory gravimetry is very important because, these methods are used to separate elements by fractional sedimentation, not only in analytical chemistry , but also in chemical engineering .