Odd electrolysis

[bob000555]

I tried electrolysis of sucrose (pure cane sugar) not expecting anything to happen. I used a 9 volt battery and two aluminum electrodes. When the electrodes got close enough a white solid was formed witch soon turned into a gas and bubbled , can anyone explain what happened. Also I think I may have synthesized methyl chloride by electrolyzing a mixture of salt and acetic acid according to Kolbe Electrolysis ethane and CO2 are formed form the acetic acid, the ethane would combine with the HCL from the salt forming methyl chloride.

[bob000555]

another grate one is a mix of ferrous sulfate and salt witch makes boatloads of hydrogen when elecrolised,but also alot of crap floats on top even with Pt eletrodes. Letds turn this into a list of cool electrolosises(sp?), like the ester list.

[YT2095]

ok, here`s an interesting one to add, try Zinc Sulphate, the Ph will be neutral at 1`st but when electrolised with carbon electrodes, the Ph will drop forming and acid soln (sulphuric acid) this will continue for a good 10-15 mins and then stabilise, you`ll have plated the Cathode with a healthy layer of Zinc, but as the Ph drops it`s also being taken Off at the same time, a Ballance is reached

 

also you`ll need a Very strong and sharp knife to remove this zinc plate off the carbon electrode. cut along its length and peel it off in one.

[woelen]

An electrolysis which leads to an interesting chemical is the following, which I did last week.

 

Take 30 ml of water.

Dissolve as much as possible of potassium bromide. You'll need approximately 10 grams.

Immerse two carbon rods in the liquid.

Run a current of 1 A for 12 hours, 2 A for 6 hours, or 4 A for 3 hours through the liquid. Carefully, but loosely cap the bottle, in order to prevent excessive spraying.

 

When done, take out the electrodes and let cool down (it becomes quite hot during the electrolysis). A thick layer of KBrO3 settles at the bottom, together with some black gunk. Put the liquid in the fridge for a while to get as much as possible KBrO3 out of it. Decant the dirty water and black gunk from the crystals. Rinse one or two times with 10 ml of ice cold water to get rid of most gunk. Now you will have raw KBrO3, which looks grey. Good enough for pyro-oxidation experiments, but for more advanced chemistry experiments you need a single recrystallization from 25 to 30 ml of hot distilled water. After that, you'll obtain an almost white solid.

 

KBrO3 can be used for many interesting redox experiments, it can also be used for making bromine in a convenient way. Be careful with KBrO3 though. It may be a (mild) carcinogen, there are indications for that. For that reason, the use as food additive is discontinued. Till the end of the 1980's KBrO3 was used as a flour enhancer, E-number E924. Also be careful when mixing KBrO3 with solid reductors, it may ignite when too much friction is applied and then it will burn very violently!!

 

The results will become even better, when a tiny pinch of potassium dichromate is added before electrolysing. Only 20 mg or so, using more is not recommended.

[woelen]

I tried electrolysis of sucrose (pure cane sugar) not expecting anything to happen. I used a 9 volt battery and two aluminum electrodes. When the electrodes got close enough a white solid was formed witch soon turned into a gas and bubbled , can anyone explain what happened.

Sucrose indeed does not lead to any interesting electrolysis reaction. However, when you used plain tap-water, then there always are dissolved salts, which will result in some ionization in the water and hence there is some slow electrolysis. The white solid will most likely be Al(OH)3. The gas is hydrogen. It is not true that the solid is converted to gas, do a more careful observation and you'll that.

 

Also I think I may have synthesized methyl chloride by electrolyzing a mixture of salt and acetic acid according to Kolbe Electrolysis ethane and CO2 are formed form the acetic acid, the ethane would combine with the HCL from the salt forming methyl chloride.

No methyl chloride will from from ethane and HCl, not under any condition. I also doubt you obtained any ethane. For making that, you need a graphite or platinum anode and a solution of sodium acetate. In that case, you onbtain CO2 and C2H6 at the anode, and H2 at the cathode. You have a salt solution and the vinegar in it hardly is ionized (it is a weak acid). With a platinum or graphite anode you'll get Cl2 at the anode, which may react a little with some vinegar, giving all kinds of chlorinated hydrocarbons, but most of the Cl2 simply will bubble out of solution.

[bascule]

Weird, you all use carbon rods for your electrodes?

 

In the past (just making hydrogen from salt water) I was using tungsten plates... never thought of using carbon rods.

[woelen]

Carbon rods are cheap, withstand strong oxidizers like Cl2 and Br2 and are easy to obtain (from zinc/MnO2 disposable batteries). Carbon anodes do erode somewhat, however, especially if the current density exceeds approximately 100 mA/cm². Carbon cathodes do not suffer from erosion.

[bob000555]

With a platinum or graphite anode you'll get Cl2 at the anode, which may react a little with some vinegar, giving all kinds of chlorinated hydrocarbons, but most of the Cl2 simply will bubble out of solution.

How would Cl2+CH3COOH make chloranated hydrocarbons?Would it be Cl2+CH3COOH->CH3Cl+HCl+CO2?

[jowrose]

Hey Woelen, what kind of disposable battery are you talking about? And how would I go about getting one...

[YT2095]

regular Zinc/Carbon batteries, the cylindrical sort like the AA or C or D cells, you can get the large quare 6 volt lantern batteries also, the plastic case comes off to reveal 4 individial cells.

 

be very carefull when taking these apart though, the black carbon and manganese dioxide paste gets everywhere and is almost impossible to get out of carpet and clothes! so out doors on a sheet of news paper is best.