Sodium hypochlorite
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Properties\n|-\n! colspan="2" align=center bgcolor="#FFDEAD" |
General\n|-\n|Name || Sodium hypochlorite\n|-\n|
Chemical formula ||
NaClO\n|-\n|
Appearance || White solid\n|-\n! colspan="2" align="center" bgcolor="#FFDEAD" |
Physical\n|-\n|
Formula weight || 74.4
amu\n|-\n|
Melting point || Decomposes at ?\n|-\n|
Density || ?\n|-\n|
Crystal structure || ?\n|-\n|
Solubility || ?\n|-\n! colspan="2" align="center" bgcolor="#FFDEAD" |
Thermochemistry\n|-\n! colspan="2" align="center" bgcolor="#FFDEAD" |
Safety\n|-\n|Ingestion || Dangerous, possibly fatal.\n|-\n|Inhalation || Dangerous, possibly fatal.\n|-\n|Skin || Causes burns, can be fatal.\n|-\n|Eyes || Causes burns.\n|-\n|More info ||
Hazardous Chemical Database\n|-\n! colspan="2" align="center" bgcolor="#FFDEAD" |
SI units were used where possible. Unless otherwise stated, standard conditions were used.Disclaimer and references
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Sodium hypochlorite is a
chemical compound with
formula NaClO. A solution of sodium hypochlorite is used as a
disinfectant and as a
bleaching agent; indeed, often it is simply called
bleach, even though other chemicals are sometimes given that name as well.
Sodium hypochlorite (like all hypochlorites) is a
salt of
hypochlorous acid, HClO. In solution, it splits into the sodium
cation Na
+ and the hypochlorite
anion ClO
-. The
oxidizing power of the latter causes the bleaching and disinfecting effect.
Packaging and sale
\nHousehold bleach sold to consumers for use in laundering clothes is a 3-6% solution of sodium hypochlorite at the time of manufacture. Strength varies from one formulation to another and decreases with storage.
High-test hypochlorite (HTH) is sold for chlorination of swimming pools and contains approximately 30% sodium hypochlorite. The crystalline salt is also sold for the same use.
Uses
\nIn household bleach form, hypochlorite is used for removal of stains from laundry. It is particularly effective on cotton fiber, which stains easily but bleaches well. Use 1/4 to 1 cup (50 to 250 ml) per load for a standard-size washer. Hot water increases the activity of the bleach.
A weak solution of household bleach of 1 oz per 1 gallon (1%) of warm water is used to sanitize smooth surfaces prior to brewing of beer or wine. Surfaces must be rinsed to avoid imparting off flavors to the brew.
A 1 in 5 dilution of household bleach with water (1 part bleach to 4 parts water) is effective against many bacteria and viruses, and is often the disinfectant of choice in cleaning hospitals. The solution is corrosive however, and needs to be thoroughly removed afterwards; sometimes the bleach disinfection is therefore followed by an ethanol disinfection.
For shock chlorination of wells or water systems, a 2% solution of household bleach (1 gallon bleach per 50 gallons system capacity) is used. For larger systems, HTH is more practical because lower rates can be used.
For purification of drinking water, about 1 quart household bleach per 1000 gallons is used. Exact amounts required depend on water chemistry, temperature, contact time, and presence or absence of sediment; in large-scale applications, residual chlorine is measured to titrate the proper dosing rate.
Cautions
\nHypochlorite is corrosive and can burn skin and cause eye damage, particularly in concentrated forms. Chloroform compounds formed when hypochlorite is mixed with organic materials (e.g. dirt) are carcinogenic. The extent of the hazard thus created is the subject of disagreement.
Bleach should never be mixed with urine or with other household cleaners, especially not with ones containing acid, since chlorine gas can form; or ammonia, since chloramine gas can form. Both chlorine gas and chloramine gas are highly toxic.
Reference numbers
\nThe CAS number of sodium hypochlorite is 7681-52-9 and the UN number of sodium hypochlorite solution is 1791.
Category:Hypochlorites
