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Dictionary:

sodium thiosulfate


n.

A white, translucent crystalline compound, Na2S2O3·5H2O, used as a photographic fixing agent and as a bleach. Also called hypo, hyposulfite; Also called sodium hyposulfite.


 
 
Dental Dictionary: sodium thiosulfate
(thī′ōsul′ fāt)
n

A powdered chemical, commonly called hypo, that is an ingredient of the fixing solution used in film processing. It clears the film of undeveloped silver halide crystals.

 
Drug Info: Sodium Thiosulfate; Salicylic Acid

Brand names: Versiclear™



Sodium Thiosulfate; Salicylic Acid skin lotion

What is Sodium Thiosulfate; Salicylic Acid skin lotion?

SODIUM THIOSULFATE; SALICYLIC ACID (Versiclear™) is used to treat a fungal infection of the skin called tinea versicolor. This fungal infection appears as white patches on the skin. Generic Sodium Thiosulfate; Salicylic Acid skin lotion is not yet available.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
• an unusual reaction to Sodium Thiosulfate; Salicylic Acid, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should this medicine be used?

Sodium Thiosulfate; Salicylic Acid skin lotion is for external use on the skin only. Do not take by mouth. Follow the directions on the prescription label. Wash hands before and after use (if treating hands, wash hands before use only). Thoroughly wash, rinse and dry the affected areas before application of the medication. Shake well and apply a thin layer of the product to cover the affected skin and surrounding area. Avoid the eyes and other sensitive areas. Use at regular intervals. Finish the full course prescribed by your prescriber or health care professional even if you think your condition is better. Do not stop using except on your prescriber's advice.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, use it as soon as you can. If it is almost time for your next dose, use only that dose. Do not use double or extra doses.

What drug(s) may interact with Sodium Thiosulfate; Salicylic Acid?

• Do not use other topical medicines on the affected area unless otherwise directed by your health care professional.

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking Sodium Thiosulfate; Salicylic Acid?

After treatment is started, your skin condition may not immediately improve or go away. It can take months to see your condition improve and your skin color to return to normal. Your prescriber or health care professional will monitor your progress to determine the best length of treatment.

Used on a regular basis, this lotion may increase sensitivity of the skin to sun or UV light. Limit sun exposure, or wear protective clothing outdoors and use a sunscreen (SPF 15 or higher). Do not use sun lamps or sun tanning beds or booths.

What side effects may I notice from receiving Sodium Thiosulfate; Salicylic Acid?

Side effects that you should report to your prescriber or health care professional as soon as possible:
• skin rash, itching or hives

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• skin irritation
• burning
• stinging

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at controlled room temperature 15—30 degrees C (59—86 degrees F).

Last updated: 4/29/2004 2:13:00 PM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

 
Columbia Encyclopedia: sodium thiosulfate,
Na2S2O3, colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3·5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo.” Sodium thiosulfate is readily soluble in water and is a mild reducing agent. Because it dissolves silver salts, its major use is in photography for developing film. It is also used in chrome-tanning leather and in chemical manufacture. Sodium thiosulfate is produced chiefly from liquid waste products of sodium sulfide or sulfur dye manufacture. It is also produced from sodium carbonate, sulfur dioxide, and sulfur by a process that involves several steps.


 
Wikipedia: sodium thiosulfate
Sodium thiosulfate
Sodium-thiosulfate-3D-vdW.png
IUPAC name Sodium thiosulfate
Other names Sodium hyposulfite
Hyposulphite of soda
Identifiers
CAS number 7772-98-7
Properties
Molecular formula Na2S2O3
Molar mass 158.09774 g/mol
Appearance White crystals
Density 1.667 g/cm³, solid
Melting point

48.3 °C

Boiling point

N/A

Solubility in water Very Soluble
Basicity (pKb) N/A
Structure
Coordination
geometry
Tetrahedral anion
Hazards
MSDS External MSDS
EU classification Non-toxic.
NFPA 704

NFPA_704.svg

0
1
0
 
R-phrases R35
S-phrases (S1/2) S26 S37/39 S45
Flash point Non flammable
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Sodium thiosulfate (Na2S2O3) (sometimes spelled thiosulphate) is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3•5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo.”

The thiosulfate anion is tetrahedral in shape and is notionally derived by replacing one of the oxygen atoms by a sulfur atom in a sulfate anion. The S-S distance indicates a single bond, implying that the sulfur bears significant negative charge and the S-O interactions have more double bond character. The first protonation of thiosulfate occurs at sulfur.

Industrial production and laboratory synthesis

On an industrial scale, sodium thiosulfate is produced chiefly from liquid waste products of sodium sulfide or sulfur dye manufacture.[1]

Small scale synthesis is by boiling an aqueous solution of sodium sulfite with sulfur.

As such, the anion S2O32− represents a water-soluble form of elemental sulfur.

Principal reactions and applications

Thiosulfate anion characteristically reacts with dilute acids to produce sulfur, sulfur dioxide and water:[1]

S2O32−(aq) + 2H+(aq) → S(s) + SO2(g) + H2O(l)

This reaction has been employed to generate colloidal sulfur. When the protonation is conducted at low temperatures, H2S2O3 (thiosulfuric acid) can be obtained. It is a strong acid pKa = 0.6, 1.7.

Iodometry

Perhaps most notably in the laboratory[citation needed], the thiosulfate anion reacts stoichiometrically with iodine, reducing it to iodide as it is oxidized to tetrathionate:

2 S2O32−(aq) + I2(aq) → S4O62−(aq) + 2 I(aq)

Due to the quantitative nature of this reaction, as well as the fact that Na2S2O3•5H2O has an excellent shelf-life, it is used as a titrant in iodometry. Na2S2O3•5H2O is also a component of iodine clock experiments.

This particular use can be set up to measure the oxygen content of water through a long series of reactions. It is also used in estimating volumetrically, the concentrations of certain compounds in solution (hydrogen peroxide, for instance), and in estimating the chlorine content in commercial bleaching powder and water.

Photographic processing

The terminal sulfur atom in S2O32− binds to soft metals with high affinity. Thus it dissolves silver halides, e.g. AgBr, which is a component of photographic emulsions:

2 S2O32− + AgBr → [Ag(S2O3)2]3−) + Br-

In this application to photographic processing, discovered by John Herschel and used for both film and paper processing, sodium thiosulfate is known as a photographic fixer.

Gold extraction

Sodium thiosulfate is one component of an alternative lixiviant to cyanide for extraction of gold.[2] It forms a strong complex with gold(I) ions, [Au(S2O3)2]3-. The advantage of this approach is that thiosulfate is essentially non-toxic and that ore types that are refractory to gold cyanidation (e.g. carbonaceous or Carlin type ores) can be leached by thiosulfate. Some problems with this alternative process include the high consumption of thiosulfate, and the lack of a suitable recovery technique, since [Au(S2O3)2]3- does not adsorb to activated carbon, which is the standard technique used in gold cyanidation to separate the gold complex from the ore slurry.

Other uses

Sodium thiosulfate is also used:

  • As a component in hand warmers and other chemical heating pads that produce heat by exothermic crystallization of a supercooled solution.
  • In Bleach
  • In pH testing of bleach substances. The universal indicator and any other liquid pH indicator are destroyed by bleach, rendering them useless for testing the pH. If one first adds sodium thiosulfate to such solutions, it will neutralize the color-removing effects of bleach and allow one to test the pH of bleach solutions with liquid indicators. The relevant reaction is akin to the iodine reaction: thiosulfate reduces the hypochlorite (active ingredient in bleach) and in so doing becomes oxidized to sulfate. The complete reaction is:
4 NaClO + Na2S2O3 + 2 NaOH → 4 NaCl + 2 Na2SO4 + H2O
  • To dechlorinate tap water for aquariums or treat effluent from waste water treatments prior to release into rivers. The reduction reaction is analogous to the iodine reduction reaction. Treatment of tap water requires between 0.1 grams and 0.3 grams of pentahydrated (crystalline) sodium thiosulfate per 10 liters of water.
  • To lower chlorine levels in swimming pools and spas following super chlorination.
  • To remove iodine stains, e.g. after the explosion of nitrogen triiodide.
  • As an antidote to cyanide poisoning. Thiosulfate acts as a sulfur donor for the conversion for cyanide to thiocyanate, catalyzed by the enzyme rhodanase.
  • In bacteriological water assessment.
  • In the tanning of leather.
  • To demonstrate the concept of reaction rate in chemistry classes. The thiosulfate ion can decompose into the sulfite ion and a colloidal suspension of sulfur, which is opaque. The equation for this acid-catalysed reaction is as follows:
    S2O32−(aq) → SO32−(aq) + S(s)
  • To demonstrate the concept of supercooling in physics classes. Melted sodium thiosulfate is very easy to overcool to room temperature and when crystallization is forced, the sudden temperature jump to 48.3°C can be experienced by touch.
  • As part of patina recipes for copper alloys.
  • Often used in pharmaceutical preparations as an anionic surfactant to aid in dispersion.

References

  1. ^ a b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5
  2. ^ Aylmore, M. G.; Muir, D. M. "Thiosulfate Leaching of Gold - a Review", Minerals Engineering, 2001, 14, 135-174

 
 

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Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
Drug Info. Gold Standard. Copyright © 2008 by Gold Standard. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium thiosulfate" Read more

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