how can you seperate sodium and chlorine from sea salt/ table salt?

Answer 1

You dissolve some salt in water. Then you let an electric current flow through the water using stainless steel as electrodes.
Then you get chlorine at the + side and hydrogen at the - electrode. You can't get sodium that way because sodium reacts very strongly with water.
But be careful. A mixture of hydrogen and chlorine is highly explosive.

Answer 2

If all you want are sodium and chlorine ions, simply dissolve in water. If you want elemental sodium and chlorine, the process is more elaborate. You need something called a Downs cell, which contains a carbon anode and an iron cathode, a perforated iron baffle to keep the Na metal and gaseous Cl2 separate, and an inverted chamber to hold the molten Na metal. See the link below for a schematic diagram. It is common to use a 40% NaCl - 60% CaCl2 mixture to lower the melting temperature to 590 ºC. You will obviously need a special furnace to reach these temperatures. An electric potential higher than 4 volts is applied to the molten salt solution (8 volts is more typical due to resistive losses), whereby electrolysis takes place, separating sodium from chlorine. You have to be a little careful that the sodium doesn't recombine with the chlorine, or you could have a little explosion on your hands.

Answer 3

when you dissolve the sodium chloride (eg in water), the ions naturally separate into Na+ and Cl- .If you then pass an electric current through the solution, the sodim goes to the cathode (the negative electrode) and the chlorine is attracted to the anode (positive elevtorde) because opposite forces attract. You could collect the chlorine as it is given off as a gas, and collect the sodium which forms a solid.