How is salt used to help the process of hydrolysis and how do you distinguish oxygen & hydrogen without fire?

Question

I have to do a prelab for my physical science class and I'm so lost! We also have to design an experiment to separate water into its component parts, and explain how hydrolysis works using the kinetic theory. thanks to anyone who answers.

Answer 1

Well in the hydrolysis of water, electricity is passed through water. Pure water is a poor conductor. If you add salt the water conducts electricity much better. The salt dissolves into ions of sodium and chloride and these ions help to form a bridge between the electrodes.

Just within the context of your experiment you know the molecular formula for water yes? Based on that formula there should be twice as much of one type of gas than the other. It should be pretty easy to tell oxygen from hydrogen on a volume basis.

Now the deeper Chemistry answer, “oxidation occurs at the anode (the negative terminal)”. It is an easy phrase to remember, and chemistry students use it often. In the case of your experiment one element is being reduced / and one is being oxidized. Oxidation means subtracting electrons (going from negative change to a neutral or positive charge). In your experiment Oxygen goes from –2 to 0, oxygen is being oxidized and it should accumulate at the anode (negative terminal).

By the way, here’s a question to stump your teacher. Most industrial generators of hydrogen work hard to remove the ions and salt from water before electrolysis, why?

Answer: oxygen is not the only thing that can be oxidized in that system. Things like chloride can also be oxidized to form chlorine gas. Which will make that funny smell tomorrow. Most of the chlorine dissolves into the water, but that makes the solution acidic, and the acid will dissolve your electrodes over time. This gets expensive if your are doing electrolysis on an industrial scale.

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