Sodium in Water Explosion

In addition to making a human battery using sodium metal, you can perform a chemistry demonstration showing the vigorous chemical reaction between sodium and water. However, it is important to use a small amount of sodium metal (a piece smaller than the size of a pencil eraser). If you use too much sodium, there is a tendency for the heat produced by the reaction to melt the remaining sodium metal, which suddenly increases the surface area available to react with water. The result may be an explosion of hot sodium metal shrapnel and lye solution.