Alcohol + sodium reaction

Question

Hi!

I wonder; why does alcohol react with sodium? How does the process look like?

Thanks!

Answer 1

Hello Lily! That kind of reaction is called an oxidation-reduction reaction, which is where one atom or moleule takes an electron (oxidizes) from another atom or molecule that holds onto electrons poorly enough that the electrons are ready to transfer off (reduced).

If you look at the periodic table, you will notice that most of the atoms are labeled "metal," and only the ones in the upper right corner, and hydrogen, are "non-metals." The most fundamental difference between metals and non-metals is that metals tend to be bad at holding onto their electrons or taking electrons from other atoms, and non-metals tend to be good at holding onto their electrons or taking electrons from other atoms.

So, in the reaction you asked about you have alcohol, which is made of non-metals, CH₃CH₂OH, and you have a metal, Na. What will happen is that the CH₃CH₂OH will take electrons from the Na.

If you are wondering about the products. Well, O does a really good job of taking electrons from anything bonded to it, and the H directly attached to it is the worst at holding onto those electrons. So, when the H on the end touches a Na, the H will take an electron from the Na, and the O will take an electron from the H. Because hydrogens are more stable as an H2 molecule than it is on its own (look up the 2-electron rule and why electrons pair up to see more about this), the H atoms will get together and form H2. When you generate H2 and also a lot of heat in a system connected to air, because transferring electrons releases a lot of heat, you tend to ignite a flame.

And that is why mixing Na and alcohol causes a flame. :-)