[holmwood]

I am trying to produce Sodium Hydroxide for a little science homework I am working on.
I initially thought about buying lye, but I heard about another method that is way more cost efficient: electrolysis.
Now my initial thought was to have a cup of water, dissolve salt to produce a salt water solution, and use some sort of an anode to start the electrolysis process.
Chlorine would be liberated from the salt, and electrolysis will bring together H20 and salt to produce Sodium Hydroxide.
However, wouldn't the chlorine gas dissolve into the compound to produce a chlorate? (If this can happen, is there any way to prevent it?)
And even if so, will electrolysis produce a sodium hydroxide that is strong enough to react to aluminum? (Let's say if I used regular batteries...)

[Sam (NG)]

Sodium Hydroxide: Methods of Production

Personally, I would buy it, it's not exactly expensive. I doubt that you can find the types of membrane required for the production from general supply stores, and the solutions produced from electrolysis require concentration by evaporation, AND they're contaminated with sodium chloride.

Stick with the easy option.  And be careful, sodium hydroxide burns are nasty.

[Borek]

I initially thought about buying lye, but I heard about another method that is way more cost efficient: electrolysis.

It can be cost efficient on the large scale, if you need grams or kilograms you will not beat the market price.

[holmwood]

Sodium Hydroxide: Methods of Production

Personally, I would buy it, it's not exactly expensive. I doubt that you can find the types of membrane required for the production from general supply stores, and the solutions produced from electrolysis require concentration by evaporation, AND they're contaminated with sodium chloride.

Stick with the easy option.  And be careful, sodium hydroxide burns are nasty.

Would reactions still work even if it was contaminated with sodium chloride? (sorry, amateur chemistry student here...)
I think I can only use dilute NAOH since I don't think high school students are even allowed to parade around school campuses with concentrated antacids.  \
(besides, even if it wasn't cost effective as the market prices.. the thought of making my own corrosive chemicals invigorates me. "not in a sick way.")

And thanks again for your quick replies. I greatly appreciate the effort you guys put into these forums.

[Sam (NG)]

I don't think that the sodium chloride will effect the reaction in this case.  But I don't think you'll get strong enough sodium hydroxide from electrolysis, besides, electrolysis without a membrane or diaphragm will just produce sodium hypochlorite/sodium chlorate solution.

Have you been asked to carry out the reaction between sodium hydroxide and aluminium?  Can you write a balanced equation for the reaction?

Are you aware of the hazards of the reactants and products in this reaction? - This is a most important question, and one that should be answered before you carry out any experimentation.  The reason I tell you this, is because when you carry out experiments in school, in general, the staff keep you isolated from the safety assessment aspect of what you are doing, and you are only allowed to carry out experiments that have already been deemed safe.  Outside of this enviroment however, it's very important to consider the dangers associated with what you are doing.

[holmwood]

I don't think that the sodium chloride will effect the reaction in this case.  But I don't think you'll get strong enough sodium hydroxide from electrolysis, besides, electrolysis without a membrane or diaphragm will just produce sodium hypochlorite/sodium chlorate solution.



Are you aware of the hazards of the reactants and products in this reaction? - This is a most important question, and one that should be answered before you carry out any experimentation.  The reason I tell you this, is because when you carry out experiments in school, in general, the staff keep you isolated from the safety assessment aspect of what you are doing, and you are only allowed to carry out experiments that have already been deemed safe.  Outside of this enviroment however, it's very important to consider the dangers associated with what you are doing.

I knew it, it does produce a chlorate! :/
My assignment was to demonstrate the effects of electrolysis on various substances. Aluminum was one of the substances that react to NAOH, so I wanted to use that to test out the result of the electrolysis of salt water.

And yes, I am well aware of the safety precautions which is why I wanted to be able to get the diluted solution of NAOH. 
Perhaps I should just try it out through electrolysis anyway, then see if it produces anything.
Maybe if I tested the chlorate with KMnO4+Glucose and see if the color change still applies.. though I doubt it'll be what I expect (highly doubt), but I already bought the materials so might as well try it anyway. :/

But say I used a membrane to allow diffusion between the cathode and anode sides of the container for electrolysis, would that produce a non chlorate solution?



Have you been asked to carry out the reaction between sodium hydroxide and aluminium?  Can you write a balanced equation for the reaction?
Here it is.
Al2O3 + 2 NaOH + 3 H2O >>> 2 Na+ + 2 AlOH4
Just showing off.. XD

Ah well, thanks for the info. I've learned alot from you guys.

[Sam (NG)]

The idea of the membrane is to hinder diffusion between the electrodes during electrolysis.  This would give you a solution of sodium hydroxide and sodium chloride.

The equation that you have written is for the reaction of aluminium oxide with aqueous sodium hydroxide.  When you react aluminium metal with sodium hydroxide you will produce aluminium hydroxide and hydrogen gas, which produces the additional hazard of extreme flammability.

Be careful with chlorate and permanganate, they're both good oxidizing agents.