Do we have a chemist?

[alanmin4304]

Do we have a chemist who can explain to this thick person how acetic acid will neutralize chlorine when decapsulating brine shrimp cysts? I understand how sodium thiosulphate works but can't get my tiny mind around what is happening with acetic acid.

[VinsonMassif]

As far as I can tell the hydrogen from the acetic acid binds to the chlorine making hydrogen chloride gas.

[georgeous]

and then the gas just, floats away.

I dont really know, just adding the (what i thought) obvious to VM's post

HTH

[Ktttk]

I'm no chemist but did a couple of searches and found the following:

The chemical reaction for chlorine bleach is:

Cl2(aq) + H2O(l) <==> 2H+(aq) + Cl-(aq) + ClO-(aq)

This is an equilibrium reaction and the addition of any acid will shift it the reaction to the left and form chlorine at the expense of ClO- (the bleaching agent) thus neurtralising it. Only problem is, chlorine gas can be poisonous.

The addition of sodium thiosulphate, however, will neutralise the chlorine bleach in a safer way by forming sodium sulphate:

4 NaClO + Na2S2O3 + 2 NaOH 4 NaCl + 2 Na2SO4 + H2O

Hope it helps.

http://en.wikipedia.org/wiki/Bleach

http://www.pburch.net/dyeing/FAQ/neutralizingdischarge.shtml

[alanmin4304]

thiosulphate actually goes to hydrochloric acid and sulphur if I remember correctly. (There is no sodium hydroxide present)

[kokako]

as far as i know acetic acid will not neutralize chlorine,

CH3COOH <==> CH3COO- + H+

acetic acid acetate hydrogen ion

H+ + Cl- <==> HCl

hydrogen ion chloride hydrogenchloride

hydrogen cloride when in solution is hydrochloric acid which is a strong acid so will mostly be dissoicated (ie mostly in the H+ and Cl- form).

some Cl- may be lost as HCl gas but this is toxic as it becomes hydrochloric acid in your lungs if you breath it in.

http://en.wikipedia.org/wiki/Hydrogen_chloride

[Slightly Blue Dalmation]

from a quick look in a chem text book acetic acid relatively weak acid so wont dissosciate much,

CH3COOH<->CH3COO- + H+

this will react with the Cl to make HCL but because HCl is a strong acid will readily dissosciate and react with water to make H3O+ and Cl-, so effectively neutralising the Cl2 to some extent as will cycle through the HCl to H3O+ etc

[Blackadder]

I think the chlorine everyone is talking about is chlorine bleach which is sodium hypochlorite.

Sodium hypochlorite reacts with excess acetic acid to give of chlorine gas.

[alanmin4304]

Sodium hypochlorate is HTH which releases 80% Cl2 W/W. This will react with water to give hypochlorous acid (HClO3). It cant release chlorine gas as it will form hypochlorous acid again.

[kokako]

Hypochlorous acid is HClO

Bleach is a mixture of NaOCl and NaCl in water.

Vinegar is CH3COOH (Acetic Acid) in water.

When you mix an acidic compound with bleach you get a mixture of HOCl, and Cl2 along with NaCl.

acetic acid liberates HOCl from the hypochlorite:

CH3COOH + ClO(-) ---> CH3COO(-) + HOCl

The HOCl then in turn reacts with chloride and another molecule of acetic acid to form Cl2:

CH3COOH + Cl(-) + HOCl ---> CH3COO(-) + H2O + Cl2

however, because acetic acid itself is a weak acid (but not as weak as HOCl). You certainly won't see strong bubbling of Cl2, but you definitely will smell it.

so it liberates as Cl2 gas not HCl gas.

[kokako]

Hypochlorous acid is HClO

Bleach is a mixture of NaOCl and NaCl in water.

Vinegar is CH3COOH (Acetic Acid) in water.

When you mix an acidic compound with bleach you get a mixture of HOCl, and Cl2 along with NaCl.

acetic acid liberates HOCl from the hypochlorite:

CH3COOH + ClO(-) ---> CH3COO(-) + HOCl

The HOCl then in turn reacts with chloride and another molecule of acetic acid to form Cl2:

CH3COOH + Cl(-) + HOCl ---> CH3COO(-) + H2O + Cl2

however, because acetic acid itself is a weak acid (but not as weak as HOCl). You certainly won't see strong bubbling of Cl2, but you definitely will smell it.

so it liberates as Cl2 gas not HCl gas.

[Slightly Blue Dalmation]

would imagine the cl2 would be in small enough amounts that wouldnt smell it and have no problems and just diffuse off

[kokako]

would imagine the cl2 would be in small enough amounts that wouldnt smell it and have no problems and just diffuse off

you're probably right at low concentrations nothing to worry about

[alanmin4304]

Thanks for that info. You are right about hypochlorous acid and I couldn't work out what was going on. It is advised to neutralize the chlorine with vinegar when decapsulating brineshrimp cysts and I couldn't get my tiny mind around how that would work. By the time you rinse the liquid off a few times there would be little chlorine left so it would not be a problem.

[Adrienne]

for a laymans explanation

disolved chlorine will stay in solution in akaline conditions but not acid conditions. The lower the pH the less disolved chlorine will remain in the water. Acetic acid is good because the pH won't drop so low as to kill off the brine shrimp but will lower the pH sufficiently to remove the chlorine.

The already posted technical answers seem correct.