Tuesday, September 18

Electrolysis Experiment

Experiment #5: Electrolysis

Lifted from Lifepac Science (Grade 10):

"Compounds are made up of elements bound together to form completely unique substances. This experiment will attempt to verify that water (H2O) is made up of hydrogen and oxygen..."


Materials Needed:
* 2 Test tubes
* 6-volt or 9-volt dry cell batteries
* 2 electrodes or tin foil
* 250ml beaker
* wooden splints
* wire with alligator clips on both ends
* candle
* 1M sodium sulfate solution (dissolve 14.2 grams sodium sulfate in distilled water and dilute to 100ml)
* piece of cardboard
* stirring rod
* ruler
* matches

* If you can not find a ready electrolysis gadget, cut holes in cardboard just large enough for the tubes to be held snugly.

* Fill test tubes with 1M sodium sulfate solution along with the 250ml beaker. Try to eliminate any trapped air in the test tubes, and fill the beaker to about 3/4 full. Invert the tubes to the solution in the beaker, keeping the open ends of the tubes submerged.
* Connect the battery (+ to -, - to +) to the other end of the wire. Connect the other end of the wire to tin foil or electrodes. Make sure the ends of the wires are secured in the open ends of the test tubes.
* Watch to make sure gas bubbles begin to form on the ends of each of the electrodes in the test tubes.
* When the tubes have significant amount of of gas collected, measure the height of the level of gas in each of the test tubes and record it.
* Slowly lift the tubes up. Be careful when handling the tubes to not let the gas escape. Place your thumb or finger over the mouth of each tube. Which of the tube holds the oxygen? Which one holds the hydrogen?
* Light the candle and use it to ignite one of the wooden splints. Blow out the splint and insert the smoldering end of the split into the tube wit the smaller amount of gas. Record results.
* Light another wooden splint and hold it at the mouth of the 2nd tube. What do you see/hear?

* Electrolysis separates H2O (water) to Hydrogen and Oxygen
* The tube with smaller amount of gas is Oxygen
* The tube with the biggest amount of gas is Hydrogen
* Hydrogen "pops" or explodes (depending on the amount of gas) when exposed to heat

Note: we were able to find an electrolysis gadget and used it instead of improvising.

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