Sodium thiosulfate pentahydrate melting point:
Sodium thiosulfate, also known as hyposulfite, is a white crystalline solid with a melting point of 48 degC. It is commonly used as a fixative for photographic film and plates and as a reducing agent in the leather tanning industry. It is a moderate reducing agent that dissolves silver salts.
Synthesis of Sodium thiosulfate:
The method of synthesis of sodium thiosulfate is the chemical reaction between dilute hydrochloric acid and sodium thiosulfate. The reaction produces sulphur dioxide and water as products.
Dehydration of Sodium Thiosulfate:
The dehydration method of sodium thiosulfate can be carried out by heating sodium thiosulfate in an indirect manner with steam. The crystals are then dissolved into a crystal water solution, which is then concentrated and evaporated to obtain an anhydrous sodium thiosulfate solution. Then the sulfate is separated and dried.
Detecting the Melting Point of Sodium Thiosulfate:
In order to measure the melting point of a substance, you need to place it near a flame. For this you will need a glass container (tube), a temperature sensor, and a burner.
Pour about 20 grams of sodium thiosulfate pentahydrate into a glass container, fixing it in the laboratory stand so that its bottom is 15 – 20 cm away from the burner. Connect the temperature sensor to your computer and set the measurement time for at least 25 minutes.
When the melt of the sodium thiosulfate pentahydrate is heated by the flame, it forms a relatively stable supercooled melt which warms up during solidification. This property is useful for generating heat in hand warmers or packages of single servings of food or drinks, as shown in Figure 1.