How to quantitatively analyze crystalline water and intermolecular water

Could you first describe the problem clearly using accurate Chinese characters?

For sodium thiosulfate separated from the centrifuge, it is unknown how many molecules of water of crystallization it contains, nor is it known what analytical method can be used to determine this quantitatively. If quantitative analysis is possible, I would like to try adjusting the process to produce products with stable crystal water. There is also concern that the product is a mixture of various crystalline hydrates. There are spelling mistakes in the text; please forgive them. Thank you for the reply.

For example, if the sodium thiosulfate content is over 64%, is it a mixture of one to four water molecules, or is it a pure substance containing a specific number of water molecules? I am looking for analysis methods for intramolecular water and intermolecular water. Intermolecular water is generally represented by loss on drying in production.

Are there any research methods for the bound water and free water of products?:) Please give me some advice, expert.

I work in process engineering and also do analysis; I’m currently looking for quantitative analysis methods for these two types of water, and since I had no idea where to start, I turned to the internet for help. There are no standardized methods for analyzing intermediate processes, and their composition is complex; it’s not easy to develop such methods on one’s own and put them into practice.

This post was last edited by qugd on 2015-8-6 at 17:32. Sodium thiosulfate with crystalline water, also known as hyposulfite, has varying degrees of stability regarding its five molecules of crystalline water. At temperatures above around 33 degrees, it loses these crystalline waters easily in a dry environment; in a humid environment, it undergoes deliquescence. When the environment is both humid and the temperature is above 44 degrees, it may even melt within its own crystalline water. Above 50 degrees, it decomposes and gradually releases its crystal water. Therefore, to determine its water content and figure out whether it is adsorbed water or crystalline water, some experimental skills and knowledge of chemistry are required. First, you need to consult relevant materials to determine the conditions under which sodium thiosulfate pentahydrate can remain stable. Analytically pure sodium thiosulfate pentahydrate should be stored in an environment that preserves its crystal water, such as a controlled-temperature and humidity chamber, to be used as a reference standard. The water content measured in the samples analyzed is compared with that of the reference sample to determine whether it is crystalline water or adsorbed water. For some of these special tests, it is necessary to design the testing methods oneself; not all testing methods have standard or ready-made approaches.

Thank you. Since sodium thiosulfate can have up to five molecules of water of crystallization, the product I’ve produced is calculated based on 3 molecules of water of crystallization; its purity is 99%, and the levels of other impurities are also within acceptable limits. It’s not clear whether it’s a mixture of multiple molecules of water of crystallization or indeed 3 molecules per molecule of the compound.

Molecular water is generally dried in an oven at 105 degrees to determine its loss in weight; this loss in weight represents the molecular water. For crystalline water, a higher temperature is required for it to lose weight. As for exactly what temperature is needed to remove a certain amount of crystalline water, it depends on the physical properties of each compound

You had better check the phase diagram of sodium thiosulfate and water in the solid state. The amount of crystal water contained is related to the conditions under which you produce it.

Yes. Thank you. I’ll look for the data.