October 22, 2012
Partner: Mike C
MASS RELATIONSHIPS IN CHEMICAL CHANGES
The purpose of this experiment was to study the fundamental idea that in chemical reactions, or changes, all particles of one substance will have the same average mass, but particles of different substances will have average masses different from each other. These changes occur in ratios, and rarely occur in simple whole numbers. When a chemical reaction occurs, how do the masses of reactants and products compare? In this experiment we will be making a comparison between the masses of reactants and products and the number of moles of reactants and products.
Polish the zinc strip using steel wool and then determine its mass. Allow the strip to sit in lead acetate for approximately an hour and observe the changes in the zinc strip. The zinc starts to accumulate particulate matter (lead particles) on its surface. This is cause by the chemical reaction that occurs between the lead acetate and the zinc strip. The strip is then rinsed in water and acetate and then dried. The particles of lead are scraped off the strip and dried thoroughly and then weighed. The mass is recorded and the zinc strip is polished again and weighed. Calculations are then done to determine the amount of zinc dissolved and the amount of lead formed. Convert the masses of the reactants and products to moles using their molar masses. Using the mole ratios from the balanced chemical equation, it is possible to determine how much material should react or be produced. These calculated values are then compared to the observed values.
In a balanced equation, the total mass of the reactants is equal to the total mass in the products. By using mole-mole factors, you can predict the moles of the product that can be produced. In this experiment...