Mammoth Memory

How did electrolysis start?

Example 1 - Electrolysis of water and sodium chloride (salt) 

Put two electrodes into a salt water solution.

Electrodes are placed in saltwater connected to a standard battery
Connect a direct current (standard battery) to the two electrodes. In this case, the electrodes are graphite, an unreactive material, and the liquid is salt water (NaCl + H2O).  

 

 

Once the circuit has been turned on the electrodes start to bubble which means giving off gas
When the circuit is switched on it is found that bubbles are formed on each electrode. So gases are being produced.

 

 

Test tubes are placed over the electrodes to catch the gas
The gases are collected and tested to see what they are. (Both are colourless)

 

The test tube from the +ve (positive) electrode (anode)

The test tube from the positive electrode, litmus paper is inserted and quickly turns red meaning chlorine is present
The damp, blue litmus paper goes red then is bleached white, which is a sure sign that the gas is chlorine.

 

 

The test tube from the -ve (negative) electrode (cathode)

The test tube from the negative electrode has a lit splint inserted, there should be a loud pop which means hydrogen is present
The lighted splint causes a “POP”, which is the test that concludes that the gas is hydrogen.

 

 

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