Separate Hydrogen and Oxygen from Water Through Electrolysis

Step 5: The Electrodes

Now take the two electrodes leading from your power source. The hydrogen will form on the positive electrode, and the oxygen on the negative. If you don't know which is which, turn on the power source and stick the electrodes in the water. The one with more bubbles is the hydrogen. Now stick the electrode underneath the gas collecting container. (turn off the power first) If you're having trouble making the gas collecting container stay up, and the electrode stay in the right place, tape it. Thats what I do anyway.

Comments

[Timofte Andrei]

salt is NaCl! so in water that green-yellowish coloured thing is chlorine! DO NOT BREATH THAT GAS! MAKE'S YOUR LUNGS LIKE A WET SPONGE AND THAT MEANS A SLOW BUT PAINFULL DEATH!

[El Mano]

They're both ionic salts. NaCl produces Cl2, baking soda produces CO; what makes NaOH the salt of choice?

[squiggy2]

all three of those salts are equally effective - it's just that health risks must be considered.

Cl2 is highly toxic to the lungs - and has immediate consequences.

Prolonged exposure to CO causes CO poisoning, where CO bonds with your red blood cells, and the can no longer take in oxygen. This will go away after a while (weeks) if you don't get it so badly that you die. ie. better than CL2

NaOH is the safest because it produces no harmful byproducts.
However, if you are in a position where you can choose salts, go for a sulfate (as mentioned below) because it does not take part in any of the reactions, so you end up with just H2 and O2.
Sulfuric acid is a good one, and it can be found in off-the-shelf cleaning products (drain cleaner?)

[gauzz]

How about Bicarbonate or Sodium bicarbonate?

[squiggy2]

Sodium bicarbonate is the scientific name for baking soda. So see El Mano's reply. But in reference to that, @El Mano I've done some reading and to me it seems that bicarbonate is a fine electrolyte and does not react at all itself, unless it gets too hot, when it will decompose into CO2. What are your sources for saying it will electrolyse to CO?

[gauzz]

Yeah txh, I'm just looking something that won't injure me or kill me, somehing that will produce the purest hydrogen and oxigen as a result.

[squiggy2]

My personal favorite is sulfuric acid. You can buy it for ~$7/L at autobarn labeled as battery acid. It's a bit dangerous as it is in the bottle, but you can dilute it with 3 parts water, or keep it as is. As long as you don't spill it, it will produce pure hydrogen and oxygen, and never deplete. Once you've bought it, it's there forever. You can have it on your skin for a few minutes without bad things happening, after which you should wash your hands, but it does destroy clothes. Also make sure you use PVC or Perspex to contain it. Coke bottles will dissolve.

[milessw]

Just a safety tip when dealing with Sulfuric Acid especially when it is concentrated...
***Always add ACID to WATER when diluting.***

Adding water to a container with pure or near pure Sulfuric acid is a bit like dropping a Mint in a soda bottle it will boil quite violently and go everywhere..

[squiggy2]

here here!

[gauzz]

That's exactly what I was looking for. I don't want to extract the oxigen to breath it, just want to be safe :)

[maestrocaldwell]

Just be careful of NaOH in high concentrations. It's a strong base, and at high concentrations it can melt your skin.

[soyers]

But your diagram shows the opposit,whith one is correct?

[hyrulianshinobi333]

cathode is negative and makes hydrogen, the diagram is wrong

[alicefangliu]

On the instruction top stated:
The water molecule is held together by the electromagnetic attraction between these ions. When electricity is introduced to water through two electrodes, a cathode (negative) and an anode (positive), these ions are attracted to the opposite charged electrode. Therefore the positively charged hydrogen ions will collect on the cathode and the negatively charged oxygen will collect on the anode.
I have same question: Cathode is negative and makes hydrogen, please
explain how is positively charged hydrogen ions will collect on the cathode
and negatively charged oxygen will collect on the anode?
So the diagram is correct? Is it the way we need to connect to battery as
your diagram showed?
Thanks.

[daddyo44907]

The diagram is wrong. Opposite poles attract. Like poles repel. The positive ions will be attracted to the negative potential -- which is the cathode. Hydrogen forms at the Cathode. Period.

If you want to test it, ignite it. Oxygen is an oxydizer, it will not burn (unless it is under pressure).

[ttatmost]

You mean Anode is negative and makes hydrogen

[dxxanthony]

you re rong cathode is positive

[scienceguy614]

cathod is negative, anode is positive.

[jarheadwithm16]

The cathode is positive. Think of ions, a ion that is a cation (the word cation probably came from the word cathode or the other way around.) has a positive charge for example: a aluminum ion has a charge of 3+..

[danbar]

the cathode is neg and the cation is positive it's inverted it just talk's about the direction of the current

[Arano]

cathions travel towards the cathode... the charges of ions and the corresponding electrode are opposite

[acem1994]

Er.. No. The Cathode is Negative and the Anode is Positive. I assure you this is true, i go to a technical school and am in Electronics, and if anyone still has any questions as to who is correct, google it. Cathode=Negative Anode=Positive

[daddyo44907]

You are absolutely correct. Positive ions do not get attracted to positive. There flow may be positive, but they are being attracted or drawn to the negative Cathode.

[shortw]

NOPE: This came from Wikipedia: * In a discharging battery or a galvanic cell the cathode is the positive terminal since that is where the current flows out of the device (see drawing). This outward current is carried internally by positive ions moving from the electrolyte to the positive cathode (chemical energy is responsible for this "uphill" motion). It is continued externally by electrons moving inwards, negative charge moving one way constituting positive current flowing the other way. * In a recharging battery, or an electrolytic cell, the cathode is the negative terminal, which sends current back to the external generator. * In a diode, it is the negative terminal at the pointed end of the arrow symbol, where current flows out of the device. Note electrode naming for diodes is always based on the direction of the forward current (that of the arrow, in which the current flows "most easily"), even for types such as Zener diodes or solar cells where the current of interest is the reverse current. * In vacuum tubes (including cathode ray tubes) it is the negative terminal where electrons flow in from the wiring and through the tube's near vacuum, constituting a positive current flowing out of the device.

[CaptInsane]

Well, I don't know how true the Wiki entries are, but apparently their charge depends on what's going on, that each can be positive or negative. http://en.wikipedia.org/wiki/Anode http://en.wikipedia.org/wiki/Cathode

[knoxarama]

That, and you can read the label on a multimeter instruction guide.

[knoxarama]

No, the polarity is set by the source. Anodes lack electrons, cathodes have a surplus, cathode is negative, which is why current always travels from the cathode, -, to the anode, +.

[CaptInsane]

I thought it was kinda funky that it's most basic answer is "it depends." Well, that's Wikipedia for ya

[Timofte Andrei]

P.S. if you want to make O2 and H2 using electrolisys use caustic soda(NaOH) instead of salt ;) sorry if i'm making any mistake. peace

[beatles1]

i just did this in sience today and our teacher told us that when u add salt the oxygen is turned into chlorine and the negative makes hydrogen and the positive makes oxygen/clorine.

[dansoffdawall]

Can you collect both oxygen and hydrogen like in the diagram showed with the negative and positive electricity?

[bigD22]

Yes, just put the anode (negative) in a test tube and the cathode (positive) in a separate test tube.

[Hockeyhero4]

Dantex, do you switch the wires too? is it supposed to be negative with positive, or positive with positive?

[Dantex]

Hydrogen is negative and oxygen positive.

[hotunderthecollar]

Thank you dantex!I was beginning to have a bit of confusion because the diagram appears to be backwards in respect to the anode and diode

[hooloovoo33]

Do you mean their respective charges, or that oxygen comes off the neg. and hydrogen off the pos. ??

[Dantex]

When you connect battery in electrolysis you get hydrogen on negative and oxygen on positive.