|MadSci Network: Chemistry|
Shellian, First of all, let me explain the basics of electrolysis. As you know, it is a method of splitting molecules. Basically, this is done by passing electric current through a container filled with salty water. In order to pass current through the water and split molecules in the process, there must be positive and negatively charged pieces of metal (called poles) at opposite ends of the container. The electric current, made up of negatively charged electrons, flows from the negative pole to the positive pole. The negative pole is called the cathode, while the positively charged pole is called the anode. The water must be salty because salt is needed to "carry" the electrons through the water from the cathode to the anode. In your experiment the salts used were potassium iodide and potassium dichromate. When current is applied and a metal containing compound such as copper sulphate is added to the water, the metal will disocciate from the rest of the molecule. You will then have positively charged copper atoms in solution. Positively charged molecules are called cations. Because opposite charges attract one another, the positively charged copper cations will be attracted to the negatively charged cathode, not the anode, in your system. Gas is given off in this system because water itself dissociates when the current is applied. The result is that hydrogen and oxygen gas are given off when electrolysis is occurring. Thank you for your question. I hope this helped. Gabriel
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