In this experiment, we will study the reaction between lead nitrate and potassium iodide. For this, we will need lead nitrate salt, potassium iodide salt, two test tubes, a test tube holder, spatula, water and a dropper. Take about half a spatula full of lead nitrate salt in a test tube and fill it up to one fourth full with water. Now shake the test tube till the salt is dissolved to prepare an aqueous solution of lead nitrate. Similarly, prepare an aqueous solution of potassium iodide in a separate test tube. Add the aqueous solution of potassium iodide to the aqueous solution of lead nitrate. You will observe a yellow colored precipitate is immediately formed in the test tube. This is lead iodide. A chemical reaction in which there is a mutual exchange of ions between the reacting compounds is called a double displacement reaction. In this reaction, lead nitrate and potassium iodide react with each other to form lead iodide and potassium nitrate. As there is a precipitate of lead iodide formed in this reaction, this is also an example of precipitation reaction.