What is Bleech made from

Annotation by rupe :

Common bleach is a diluted sodium hypochlorite solution. Here's the MSDS, taken from http://hazard.com/msds2/f/98/ckvft.html:

CLOROX CO.,                    -- CLOROX GERMICIDAL BLEACH                     
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MSDS Safety Information 
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MSDS Date: 02/01/1998
MSDS Num: CKVFT
Product ID: CLOROX GERMICIDAL BLEACH
MFN: 02
Responsible Party
Cage: 4T284
Name: CLOROX CO., THE
Address: 1221 BROADWAY
Box: UNKNOW
City: OAKLAND CA 94612
Info Phone Number: 510-271-7000
Emergency Phone Number: 510-847-6100
Review Ind: Y
Published: Y
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Preparer Co. when other than Responsible Party Co. 
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Cage: GO490
Assigned Ind: Y
Name: CLOROX CO  (HEADQUARTERS)
Address: 1221 BROADWAY
Box: 24305
City: OAKLAND CA 94623
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Contractor Summary 
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Cage: 93098
Name: CLOROX CO THE  HEADQUARTERS
Address: 1221 BROADWAY
Box: 24305
City: OAKLAND CA 94612-1305
Phone: 510-271-7000
Cage: 4T284
Name: CLOROX CO., THE
Address: 1221 BROADWAY
Box: UNKNOW
City: OAKLAND CA 94612
Phone: 510-271-7000
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Ingredients 
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Cas: 7681-52-9
RTECS #: NH3486300
Name: SODIUM HYPOCHLORITE
Percent by Wt: 5.25
EPA Rpt Qty: 100 LBS
DOT Rpt Qty: 100 LBS
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Health Hazards Data 
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Route Of Entry Inds - Inhalation: YES
Skin: NO
Ingestion: YES
Carcinogenicity Inds - NTP: NO
IARC: NO
OSHA: NO
Effects of Exposure: EYE IRRITANT.  AVOID EYE CONTACT.	CAUSES SUBSTANTIAL BUT
  TEMPORARY EYE INJURY.  MAY IRRITATE SKIN.
Explanation Of Carcinogenicity: NONE
Signs And Symptions Of Overexposure: MAY CAUSE NAUSEA AND VOMITING IF INGESTED.
  EXPOSURE TO VAPOR OR MIST MAY IRRITATE NOSE, THROAT AND LUNGS. UNDER NORMAL
  CONSUMER USE CONDITIONS THE LIKELIHOOD OF ANY ADVERSE HEALTH EFFECTS ARE LOW.
  OCCASIONAL CLINICAL REPORTS SUGGEST A LOW P OTENTIAL FOR SENSITIZATION UPON
  EXAGGERATED EXPOSURE TO SODIUM HYPOCHLORITE IF SKIN DAMAGE OCCURS DURING
  EXPOSURE. ROUTINE CLINICAL TESTS CONDUCTED ON INTACT SKIN WITH CLOROX LIQUID
  BLEACH FOUND NO SENSITIZATION IN THE TEST SUBJECTS.
Medical Cond Aggravated By Exposure: HEART CONDITIONS OR CHRONIC RESPIRATORY
  PROBLEMS SUCH AS ASTHMA, CHRONIC BRONCHITIS OR OBSTRUCTIVE LUNG DISEASE.
First Aid: EYES: IMMEDIATELY FLUSH W/PLENTY OF WATER. SKIN: WASH AREA W/WATER.
  INGESTION: DRINK A GLASSFUL OF WATER. INHALATION: REMOVE TO FRESH AIR. OBTAIN
  MEDICAL ATTENTION IN ALL CASES.
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Handling and Disposal
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Spill Release Procedures: ABSORB, CONTAINERIZE & LANDFILL IN ACCORDANCE
  W/LOCAL REGULATIONS. WASH DOWN RESIDUAL TO SANITARY SEWER. PUMP MATERIAL TO
  WASTE DRUMS & DISPOSE. FOR SPILLS OF MULTIPLE PRODUCTS, RESPONDERS SHOULD
  EVALUATE THE MSDS'S OF THE PRODUCTS FOR INCO MPATIBILITY WITH SODIUM
  HYPOCHLORITE. BREATHING PROTECTION SHOULD BE WORN IF ENCLOSED, AND/OR POORLY
  VENTILATED AREAS UNTIL HAZARD ASSESSMENT IS COMPLETE.
Waste Disposal Methods: DISPOSE OF IN ACCORDANCE WITH ALL APPLICABLE FEDERAL,
  STATE AND LOCAL REGULATIONS.
Handling And Storage Precautions: DISPENSING SYSTEM: EYE PROTECTION ISN'T
  REQUIRED WHEN USED W/A CLOROX APPROVED CLOSED DISPENSING SYSTEM. DILUTED TO
  200PPM AVAILABLE CHLORINE: EYE PROTECTION ISN'T REQUIRED. DISCONTINUE USE OR
  WEAR GLOVES IF SOLUTION IRRITATES YOUR SKIN.
Other Precautions: KEEP OUT OF THE REACH OF CHILDREN. PRODUCT IS A
  STRONGOXIDIZING AGENT.
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Fire and Explosion Hazard Information 
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Fire Fighting Procedures: IN A FIRE, COOL CONTAINERS TO PREVENT RUPTURE &
  RELEASE OF SODIUM CHLORATE.
Unusual Fire/Explosion Hazard: NON-FLAMMABLE/EXPLOSIVE.
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Control Measures 
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Ventilation: GENERAL VENTILATION TO MINIMIZE EXPOSURE TO VAPOR OR MIST
Protective Gloves: WEAR IF PRODUCT IRRITATES SKIN
Eye Protection: SAFETY GLASSES
Work Hygienic Practices: REMOVE/LAUNDER CONTAMINATED CLOTHING BEFORE REUSE.
Supplemental Safety and Health: HAZARD RATING: HEALTH=2, FLAMMABILITY=0,
  REACTIVITY=1
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Physical/Chemical Properties 
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Boiling Point: =100.C, 212.F
Spec Gravity: 1.085
PH: 11.4
Solubility in Water: COMPLETE
Appearance and Odor: CLEAR, LIGHT YELLOW LIQUID W/CHLORINE ODOR
=======================================================
Reactivity Data 
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Stability Indicator: YES
Stability Condition To Avoid: PROLONGED CONTACT WITH METAL MAY CAUSE PITTING OR
  DISCOLORATION.
Materials To Avoid: VINEGAR, ACIDS, AMMONIA, TOILET BOWL CLEANERS, RUST
  REMOVERS
Hazardous Decomposition Products: HAZARDOUS GASES, CHLORINE & OTHER CHLORINATED
  SPECIES.
Hazardous Polymerization Indicator: NO
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Toxicological Information 
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Ecological Information 
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MSDS Transport Information 
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Transport Information: PROPER SHIPPING NAME: HYPOCHLORITE SOLUTION WITH NOT
  MORE THAN 7% AVAILABLE CHLORINE.  NOT RESTRICTED PER 49CFR172.101
  (C)(12)(IV).
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Regulatory Information 
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Sara Title III Information: BOTTLED PRODUCT IS NOT REPORTABLE UNDER SECTIONS
  311/312; CONTAINS NO CHEMICALS REGULATED UNDER SECTION 313; AND CONTAINS A
  CHEMICAL (SODIUM HYPOCHLORITE<5.25%) WHICH IS REGULATED UNDER SECTION
  304/CERCLA.
Federal Regulatory Information: ALL CHEMICALS IN THIS PRODUCT ARE LISTED ON THE
  TSCA INVENTORY AND THE CANADIAN DOMESTIC SUBSTANCES LIST.
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Other Information 
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HAZCOM Label 
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Product ID: CLOROX GERMICIDAL BLEACH
Cage: 4T284
Company Name: CLOROX CO., THE
Street: 1221 BROADWAY
PO Box: UNKNOW
City: OAKLAND CA
Zipcode: 94612
Health Emergency Phone: 510-847-6100
Label Required IND: Y
Date Of Label Review: 10/20/2000
Status Code: A
Origination Code: G
Hazard And Precautions: EYE IRRITANT.  AVOID EYE CONTACT.  CAUSES SUBSTANTIAL
  BUT TEMPORARY EYE INJURY.  MAY IRRITATE SKIN.
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Disclaimer (provided with this information by the compiling agencies): This
  information is formulated for use by elements of the Department of Defense.
  The United States of America in no manner whatsoever expressly or implied
  warrants, states, or intends said information to have any application, use or
  viability by or to any person or persons outside the Department of Defense
  nor any person or persons contracting with any instrumentality of the United
  States of America and disclaims all liability for such use. Any person
  utilizing this instruction who is not a military or civilian employee of the
  United States of America should seek competent professional advice to verify
  and assume responsibility for the suitability of this information to their
  particular situation regardless of similarity to a corresponding Department
  of Defense or other government situation.