9. Deflecting A Water Stream With A Charged Rod

The Science: A stream of water contains polar water molecules. One side (hydrogen side) has a slightly positive charge. The oxygen side has a slightly negative charge. So if a charged rod is brought close to the stream, the water will be attracted to it. If the rod is positively charged, the slightly negative side of the water molecule will be attracted toward the rod. Likewise, if a negatively charged rod is brought close to it, the hydrogen side will be attracted to the rod and the oxygen side will be “repelled.” In both cases, the water stream will be attracted to the charged rod.

10. Hydrogen Peroxide Mixed With Potassium Iodide

The Science: This experiment is often used as a fun science demo for kids…It is called “Elephant’s Toothpaste.” Hydrogen peroxide is catalytically decomposed by the potassium iodide. By the iodide ion, actually. Oxygen gas is rapidly formed. You put a squirt of dish soap and a drop of food coloring into 50 mL of 30% hydrogen peroxide… Then when you add 1 or 2 grams of potassium iodide… the released oxygen gas is trapped in soap bubbles… you get a huge amount of foamy suds!!! The reaction sequence is as follows:

H202 (aq) + I- (aq) –> H20 (l) + OI- (aq)

H202 (aq) + OI- (aq) –> H20 (l) + O2 (g) + I- (aq)

The iodide ion is not consumed by the reaction, therefore it is a CATALYST.