Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Hadrian on 07/12/2006 16:05:39

Title: what is the connection between salt water and bleach?
Post by: Hadrian on 07/12/2006 16:05:39

Can you explain the connection between salt water and bleach?

Title: Re: what is the connection between salt water and bleach?
Post by: lightarrow on 08/12/2006 14:31:08

You can make bleach NaClO, in these 2 ways, for example:
 
1) Add chlorine Cl₂ to sodium hydroxide NaOH. Bleach and kitchen salt (NaCl) is formed:

2NaOH + Cl₂ → NaClO + NaCl + H₂O

2) By electrolysis of salt water:

At the + electrode (Anode): 2Cl^- → Cl₂ +  2e^-

At the - electrode (Cathode): 2Na⁺ + 2e^- → 2Na;      2Na + 2H₂O → 2NaOH + H₂↑

The gaseous hydrogen H₂ leaves the solution, the gaseous chlorine Cl₂ dissolves in it and react with NaOH according to the first equation I wrote.

Title: Re: what is the connection between salt water and bleach?
Post by: eric l on 08/12/2006 18:21:11

Actually, industrial electrolysis of salt uses either a diaphragm to separate the chlorine from the solution or a mercury cathode to dissolve The sodium if you do not want to end up with bleach !