This video was produced by... This demonstration has safety risks. Because of these risks, we wear clothes to choose and safety goggles. This demonstration should only be done by a trained professional and should not be tried at home. Hi, I'm Casey Rogers and I'm coming to you from the Department of Chemistry and Biochemistry at James Madison University. The demonstration I'm going to do today is called Rates of Yellow. Here I have two white solids. The first is lead nitrate and the second is potassium iodide. I'm going to combine these two together in the same bile. And then I'm going to shake. By shaking, I'm inputting mechanical energy and so this is going to be a mechanical chemical process. Lead nitrate and potassium iodide combine to form lead iodide, which is yellow, and potassium nitrate, which is white. I'm going to shake it a little longer here so if I can get the reaction to go a little more. As you can see, we now have some of a yellow solid in the vial showing that lead iodide was produced. I'm going to do this reaction again, but this time instead of the reactions being solids, I'm going to have the reactants in aqueous solution. So as we can see, they're both colorless liquids and so then when I add them to the vial, we'll see what happens. A few drops of lead nitrate and then a few drops of potassium iodide. As you can see, this reaction almost instantaneously produced a precipitate of yellow lead iodide. There's also some aqueous potassium nitrate there. But this reaction happened a lot faster than the solid phase reaction. The solid phase reaction took longer and required an input of energy. In general, aqueous reactions tend to occur faster than solid phase reactions because the ions are mobile and free flowing in solution, thus it's easier for them to react. And the solid phase reaction could only happen as the solid particles of lead nitrate and potassium iodide rubbed against each other. As you notice, during this demonstration, I was wearing gloves because lead is toxic to humans and the environment. So I was wearing gloves to protect myself and then these chemicals will be disposed of properly since the demonstration is now over. This has been Casey at James Madison University. Thank you for watching.