Sodium thiosulfate pentahydrate (Na2S2O3 · 5H2O) is a crystalline compound that dissolves easily in water. It is commonly used in photographic processing and as a medical antidote for cyanide poisoning.
| IUPAC Name | Sodium thiosulfate pentahydrate |
| Molecular Formula | Na2S2O3 · 5H2O |
| CAS Number | 10102-17-7 |
| Synonyms | Sodium hyposulfite pentahydrate, Sodium thiosulphate pentahydrate, Sodium thiosulfate hydrate, Sodium thiosulfate 5-hydrate |
| InChi | InChI=1S/2Na.H2O3S2.5H2O/c;;1-5(2,3)4;;;;;/h;;(H2,1,2,3,4);51H2/q2+1;;;;;;/p-2 |
Sodium Thiosulfate Pentahydrate Properties
Sodium Thiosulfate Pentahydrate Formula
The chemical formula of sodium thiosulfate pentahydrate is Na2S2O3 · 5H2O. It consists of two Na+ ions, two (S2O3)2- ions, and five water molecules. The compound has a white crystalline appearance and is highly soluble in water.
Sodium Thiosulfate Pentahydrate Molar Mass
The molar mass of Na2S2O3 · 5H2O is 248.18 g/mol. It is the sum of the atomic masses of sodium, sulfur, oxygen, and hydrogen in the compound. The molar mass is an important parameter in chemical calculations, including determining the amount of a substance required for a reaction.
Sodium Thiosulfate Pentahydrate Boiling Point
Na2S2O3 · 5H2O does not have a specific boiling point since it decomposes when heated. Instead, it undergoes a thermal decomposition process that results in the release of water vapor and sulfur dioxide gas. The decomposition temperature of Na2S2O3 · 5H2O is around 48°C.
Sodium Thiosulfate Pentahydrate Melting Point
The melting point of Na2S2O3 · 5H2O is 48.3°C. At this temperature, the compound undergoes a phase change from a solid to a liquid. Na2S2O3 · 5H2O has a relatively low melting point, which is attributed to the presence of the water molecules in its crystal structure.
Sodium Thiosulfate Pentahydrate Density g/mL
The density of Na2S2O3 · 5H2O is 1.67 g/mL. The compound has a relatively high density compared to other salts, which is due to the presence of multiple ions in its crystal structure. The density of a substance is defined as the amount of mass per unit volume.
Sodium Thiosulfate Pentahydrate Molecular Weight
The molecular weight of Na2S2O3 · 5H2O is 248.18 g/mol. It is the sum of the atomic weights of the elements present in the compound. The molecular weight is an important parameter in chemical calculations, including determining the stoichiometry of a reaction.
Sodium Thiosulfate Pentahydrate Structure
The crystal structure of Na2S2O3 · 5H2O is composed of sodium cations, thiosulfate anions, and water molecules. The sodium ions are located at the corners of the unit cell, while the thiosulfate anions and water molecules are arranged in a layered structure. The thiosulfate anions and water molecules form chains that run along the c-axis of the unit cell.
Sodium Thiosulfate Pentahydrate Solubility
Na2S2O3 · 5H2O is highly soluble in water. The solubility of a substance is defined as the maximum amount of the substance that can be dissolved in a given amount of solvent at a specific temperature and pressure. The solubility of Na2S2O3 · 5H2O in water increases with temperature, and it is used in various industrial and medical applications.
| Appearance | White crystalline solid |
| Specific Gravity | 1.67 g/mL |
| Color | White |
| Odor | Odorless |
| Molar Mass | 248.18 g/mol |
| Density | 1.67 g/mL |
| Melting Point | 48.3°C |
| Boiling Point | Decomposes at 48°C |
| Flash Point | Not applicable |
| Water Solubility | Highly soluble |
| Solubility | Soluble in water and glycerol |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 7.2 |
| pH | 6.5-9.5 (5% solution in water) |
Sodium Thiosulfate Pentahydrate Safety and Hazards
Na2S2O3 · 5H2O is generally considered safe to handle and use. However, it can cause irritation to the eyes, skin, and respiratory system. Ingestion of large amounts of Na2S2O3 · 5H2O may cause gastrointestinal disturbances. It is also important to avoid contact with oxidizing agents and strong acids, as it may react violently with these substances. Na2S2O3 · 5H2O is not considered a fire or explosion hazard, but it may emit toxic fumes when heated to decomposition. As with all chemicals, proper precautions should be taken when handling and using Na2S2O3 · 5H2O to minimize any potential risks.
| Hazard Symbols | None |
| Safety Description | S24/25 – Avoid contact with skin and eyes |
| UN IDs | Not regulated |
| HS Code | 2832.10.00 |
| Hazard Class | Not classified as hazardous according to GHS |
| Packing Group | Not applicable |
| Toxicity | LD50 (oral, rat): > 6,000 mg/kg |
Sodium Thiosulfate Pentahydrate Synthesis Methods
Various methods can synthesize Na2S2O3 · 5H2O.
One common method involves the reaction of sodium sulfite with sulfur under alkaline conditions. Another method involves the reaction of sodium hydroxide with sulfur dioxide, followed by the addition of sulfur. Upon heating the mixture, it produces Na2S2O3 · 5H2O.
To synthesize Na2S2O3 · 5H2O, chemists react sodium sulfide with sulfur dioxide, resulting in the formation of sodium sulfite. Then oxidize the sodium sulfite using hydrogen peroxide or chlorine to form sodium sulfate. The reaction of sulfur with sodium sulfate takes place under alkaline conditions, and the resulting mixture undergoes heating to yield Na2S2O3 · 5H2O.
It is important to note that the synthesis of Na2S2O3 · 5H2O should be carried out with proper safety precautions, such as the use of protective equipment and proper ventilation. Additionally, the purity of the starting materials and the reaction conditions can affect the yield and purity of the final product.
Sodium Thiosulfate Pentahydrate Uses
Na2S2O3 · 5H2O has a variety of uses across different industries due to its unique properties. Some of its common uses include:
- Photography: It actively functions as a photographic fixer to eliminate unexposed silver halide from photographic film.
- Medical: Used as an antidote to cyanide poisoning, as it can react with cyanide to form the less toxic thiocyanate.
- Water treatment: Used to remove chlorine from water, which is important in industries such as swimming pools, aquariums, and wastewater treatment.
- Analytical chemistry: Used as a reducing agent in titrations and as a complexing agent in the determination of heavy metals.
- Agriculture: Used as a fertilizer to correct sulfur deficiencies in plants.
- Textile industry: Also used as a bleaching agent for wool and silk fabrics.
- Gold mining: Used in gold mining to extract gold from ores by leaching.
- Other uses: Commonly used in the production of paper, in the manufacture of dyes, and as a laboratory reagent.
Questions:
Q: How many grams of sodium thiosulfate pentahydrate would be needed to prepare 250.0 ml of 0.1000 M?
A: To prepare 250.0 ml of 0.1000 M solution of Na2S2O3 · 5H2O, you would need 9.944 grams of Na2S2O3·5H2O.
Q: How to dilute sodium thiosulfate pentahydrate?
A: Na2S2O3 · 5H2O can be diluted by dissolving it in water. The amount of water required depends on the desired concentration of the solution.
Q: How many grams of solid sodium thiosulfate pentahydrate are needed to prepare exactly?
A: The amount of solid Na2S2O3 · 5H2O needed to prepare a solution depends on the desired concentration and volume of the solution. You can use the formula C1V1 = C2V2, where C1 and V1 are the initial concentration and volume, respectively, and C2 and V2 are the final concentration and volume, respectively, to calculate the amount of solid required.
Q: What is sodium thiosulfate pentahydrate used for?
A: Na2S2O3 · 5H2O is used in photography, medical industry, water treatment, analytical chemistry, agriculture, textile industry, gold mining, paper production, dye manufacturing, and as a laboratory reagent.
Q: Who sells sodium thiosulfate pentahydrate?
A: Na2S2O3 · 5H2O is sold by various chemical suppliers and distributors, both online and offline. Some examples include Sigma-Aldrich, Fisher Scientific, and VWR International.
Q: What can I use in place of Na2S2O3·5H2O for quenching any reactions?
A: There are various chemical compounds that can be used as an alternative to Na2S2O3 · 5H2O for quenching reactions, depending on the specific reaction and requirements. Some examples include urea, hydroxylamine hydrochloride, and sodium bisulfite.
Q: What is Na2S2O3·5H2O?
A: Na2S2O3·5H2O is the chemical formula for Na2S2O3 · 5H2O, which is a white crystalline compound that is used in various industrial and laboratory applications.