Both potassium and iodide ions have a single charge hence the potassium iodide molecule contains one ion each. The nitrate ion has a single negative charge while lead has \ charge, therefore two nitrate ions will be present in a single molecule of lead nitrate (charge must be balanced in an ionic salt). The reaction between lead (II) nitrate and potassium iodide is a double displacement reaction in which the anions of both the ionic salts get exchanged. Thus, the total number of atoms of each element present on the reactant side must be the same as that of the product side. If the mass remains conserved before and after a reaction takes place, then the number of atoms of each element participating in a reaction should also remain the same. it is not possible to create or destroy the mass of atoms in a reaction. According to this law the total matter in a reaction remains conserved i.e. One of these laws is the Law of conservation of mass. The reactant and products can then be multiplied by suitable stoichiometric coefficients.Ĭhemical reactions can be written on the basis of certain laws of chemical combination. The solution now contains only potassium nitrate and baking soda, and can be poured down the drain with plenty of water.Hint: Both the reactants and the products are ionic salts that are neutral molecules, hence their formulas can be written by balancing their charges. The lead carbonate precipitate can be filtered off and disposed of as regular garbage. The lead iodide is slightly soluble whereas the lead carbonate is totally insoluble. This will cause the solutions to go cloudy with a lead carbonate precipitate. Make a hot, saturated solution of bicarbonate and use it to treat anything that came in contact with the lead-bearing solutions. We need to ensure that all of the soluble lead has been eliminated. Cleanup and disposal of the waste solution is an important point. Carefully remove the tiny crystals on the filter paper to obtain a very beautiful sheet of golden coloured lead iodide.ħ. Place the flask in the lab fridge overnight. This time, because of the slow cooling, it forms extremely thin hexagonal plate-like crystals that shine and glitter as they move around the solution. This causes the lead iodide to precipitate back out of solution. Turn off the heat and allowed the flask to cool to room temperature on its own. This happens because lead iodide is almost ten times more soluble in hot solution than in cold.ĥ. Take the flask containing the lead iodide and heat it to near boiling on a hot plate until all of the yellow crystals dissolved and the solution is clear. (Pouring the potassium iodide solution into the lead nitrate was a safety measure to minimize handling the lead solution as much as possible).Ĥ. A bright yellow precipitate (lead iodide) is produced from two clear solutions.
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