People are not allowed to use aluminum utensils to make soap. Why?

Question

During a kitchen chemistry class, I was asked why no one should use aluminum utensils to make soap. I made a simple chemical reaction equation: Al + NaOH = Al(OH)3 + 3Na

The only problem is that my equation will cause a runaway reaction as the sodium hydroxide (NaOH) is aqueous. Water reacts *explosively* with elemental sodium to form more sodium hydroxide. So this equation defies logic.

Is the equation correct? If not, why am I not allowed to use aluminum utensils for soap making from olive oil?

Answer 1

You missed a three. And If the equation is correct (i'm gonna be lazy and assume you are right), It probably would be a bad Idea since "explosively" is an understatement.

Answer 2

The reaction product is sodium aluminate, NaALO2, and hydrogen in alkaline conditions.  Balance it again.  So it will dissolve the aluminum and make flammable hydrogen.

Answer 3

Right now you have a formula to a reaction, and you're wondering whether it will happen or not.  Whenever a chemist has this problem, we turn to Spontaneity.  Spontaneity, or Gibb's Free energy, tells you what direction to write that arrow (I don't know why you have an equals sign.  The reaction will either go left to right, right to left, or be in equilibrium.  We don't put equals signs there).  

How do you know if a reaction occurs?  You use the equation "Delta G = Delta H - T * Delta S".  Basically, the gibb's free energy number (negative is spontaneous, positive is that the reverse reaction is spontaneous, zero is in equilibrium) is equal to the change in enthalpy (enthalpy is kind of like heat) minus the temperature in degrees kalvin times the change in entropy.  And thus you can find out if any reaction is spontanous or not.  Just look up the specific values for the chemicals involved.  

Now, I can tell you right now that creating sodium (Na) is Not Spontaneous.  Definitely not.  I would assume that the reaction would more properly read as Na -> NaOH  simply because Sodium Hydroxide is the spontaneously formed compound, not sodium.  If there is a massive explosion, that's a way of telling you it's very, very energetically unfavorable for sodium to be in its Na+ (metal) form.  The NaOH is the energetically favorable form.  

IN PLAIN ENGLISH:  Sorry for all the chemistry talk.  My point is that the formula you listed is not spontaneous and will not happen unless you provide energy to the system.  So, basically, that reaction will not happen and is Not the reason why aluminum isn't used.  There must be some other reason.  I don't know why you can't use aluminum in cooking (I'm a chemist, not a chef), but it's not because you'll make sodium metal and blow up your kitchen.  Lol, that's just not happening.

Answer 4

Leo is correct.

Aluminium is an amphoteric metal and will react with both acids and alkalis.  Admittedly it does so slowly very often because of the layer of aluminium oxide on the surface of any piece of aluminium.  But once that layer is removed the metal can react very rapidly indeed

So the product will be sodium aluminate [NaAlO2 or NaAl(OH)4 ] and hydrogen