Electrolysis

Intro: Electrolysis

Electrolysis is the decomposition of hydrogen and oxygen in water. In other words you break apart the molecules that make up water to restore the elements to their original state. In this case both hydrogen and oxygen exist in a gaseous state. In order to perform electrolysis you must run an electric current through water that contains an electrolyte. The electrolyte allows current to pass through the water because pure water, or even tap water for that matter, is not conductive enough to allow electricity to pass through it. The electrolyte I added in this experiment was salt, a common household item.

STEP 1: Getting the Stuff

The materials you will need for this experiment are:

baking soda (it used to be salt but then I was informed that I may have been producing chlorine gas)

Hot water (enough to fill your container of choice)

a container preferably air-tight and definitely clear

a pair of screws (these will act as the electrodes you pass the
current through)

a battery (a nine volt will do nicely for your first try)

Space to work (I barely had any and that made it a lot tougher)

Materials you may want to have, but are not necessary:

a glue gun (to patch up any holes left by the electrodes)

a DC power source so you don't have to worry about the batteries
running out.

a container that can dispense the hydrogen and oxygen (see introduction)

STEP 2: Build the Cell

Once you've gathered all of the materials you will want to start by drilling two holes at the bottom of your container. (I drilled them at the top) You'll want these holes to be just slightly smaller than the screws you'll be putting through them. You will want the two screws to be as close as possible to each other so as to get the maximum effect when electrolyzing the water. Once you have paced the screws in you may want to hot glue around them so as to create a seal.

STEP 3: Baking Soda-water Mixture

Tos start this you will want to heat up enough water to fill your container the heat helps saturate the baking soda within the water. Once you have heated the water you will then need to pour baking soda into the water while stirring (don't be shy about this you can saturate a lot of baking soda in hot water.) Dont' let any baking soda gather on the bottom of the container it will effect conductivity.

STEP 4: Setting Up the Cell

Once you have placed the screws in and mixed in the salt you'll want to get to the main event. Pour the water into the container and place the cap on. Then place the battery, or batteries if your ambitious on the two electrodes. This will create a stream of bubbles that emanate from the probe connected to the negative end of the battery.

STEP 5: The Science of Electrolysis

What you will have just witnessed is the separation of hydrogen and oxygen. The negative probe will always produce hydrogen whereas the positive will always produce oxygen. The reason you see very few bubbles coming from the positive end is the result of there being less oxygen in water than there is hydrogen thus resulting in more bubbles of hydrogen than oxygen.

STEP 6: Trouble Shooting

You may have encountered some of these probelms during the operation of the cell. The stream may have stopped flowing from the negative and positive end, this may be the result of an insuffiecient connection between the two probes so adjust the position of the battery and the flow will restart. The bubbles may have never been created and that would be the couse of either a dead battery which if your brave enough (unlike some people I know -*Cough*Gerid*cough*-) you can test on your tongue. This may also be the result of non-conductive probes. To fix the latter you will have to find new METAL screws.

Comments

[bylerfamily]

Alright,I was gonna post some pics of my hydrogen generators but I can't find the cord so I will tell you about them.My first one is a little clear plastic container that used to contain glycerin.It has a coil of wire that runs into the water.The positive is a thick piece of wire that runs down the middle of the coil.It is powered by a 4v 550ma wall wart.My second is really awesome.It is made with a 5 gallon bucket.It has a thick rod running down the middle of the coil.It has a piece of 1/2 inc PVC for the output because a bottle easily and smoothly fits over a piece of 1/2.It is powered by a car battery charger so I can push 2-50 amps through the water.When it is running at 10A you can feel the gas coming out the pipe.I will post pics as soon as I get the camera cord.

[GrahamRounce]

Hi - how much baking soda did you use for 5 gallons?
Thanks,

[GrahamRounce]

Doesn't the water get really hot with 10A @ 12V = 120W ?
Thanks,

[wolfmain]

Baking soda works perfectly fine, I would know, the carbonate poly atomic anion won't break up, but if you're really picky, use sulfuric acid. Your electrolyte must be made of a group 1 or 2a group metal cation (check periodic table) and A poly atomic anion, such as SO4 or CO3. If it's a halogen, you'll get the halogen gas instead of oxygen, and a hydroxide in your water. Halogens can kill you. Use graphite for you positive electrode and copper wire for your negative.

[GrahamRounce]

Hi - how much baking soda should I use per litre (or gallon) of water?
Thanks,

[MarioL111]

It only takes about 15V to split pure water, less for water that has been allowed to absorb CO2 from the air. Less than 1V for sea water.

[bobdabiulder]

When I did this with aluminum foil, it would not work if both electrodes were the same metal. One had to copper or something else.

[LabRatMatt]

Aluminum is not the best metal for this particular project. You're much better off using stainless steel if you can find some.

[MarioL111]

SS is about 10% Cr, so it should be avoided. Nickel, silver, and graphite rods are good choices. I use graphite rods from old non-alkaline D batteries. They are about 55mm long and 8mm diameter.

[russjd]

pair of screws (these will act as the electrodes)

is there a better material to use than steel screws?

(Screws are generally made from low to medium carbon steel wire, but other
tough and inexpensive metals may be substituted, such as stainless steel,
brass, nickel alloys, or aluminum alloy. Steel may be coated or plated with zinc, cadmium, nickel, or
chromium for extra protection).

[LabRatMatt]

Steel plates are probably your best option. Anything else will oxidize (rust) immediately

[darkath]

wait....... i though hydrogen is off the positive lead..... I am so confused right now.

[Lewissunn]

Okay, 6 months late but i'll explain anyway.

H2O

Hydrogen in water has a charge of +1

Oxygen has a charge of -2

The negative lead attracts the hydrogen because it is the oppisite charge

[HenryFlack]

Interesting ....

[LandonSalvador]

Wow great experiment....

[trickery89.]

Nice, I'm going to try this soon!

[PetieE]

I'm not sure if this entirely applies to this electrolytic cell, but I am recovering a steel plate with electrolysis for an EEI, and I need to know if using baking soda and water as the electrolyte will produce harmful gases or anything of the sort. I have to choose between NaOH or the baking soda and water. I need the half reaction to support my decision (I suck at doing half reactions and I don't always understand how to do them). If someone could help, it would be much appreciated

[BBoyBravo]

how do you stop the electrodes and water from getting guey! I' tried more soda, less soda, distilled water, well water, bottled water it always seems to fry the electrodes and it still gets all guey

[dknutson]

Simple: use stainless steel plates, and KHO flakes as your electrolyte. Salt produces chlorene gas, bakeing soda produces carbon monoxide!

[tyu123456789]

If you put baking soda in it, it will only make carbon dioxide not carbon monoxide because carbon monoxide is made when carbon dioxide is heated or if theirs not enough oxygen to combine with the carbon atom.