Period 3
March 8, 2013
Lab Report: Empirical Formula of Zinc Chloride (ZnCl) * Purpose
The purpose of this experiment was to learn how to determine the empirical formula. Empirical means “based on experimental evidence.” * Experimental Design
The reaction that occurred was the reaction of the elements Zinc (Zn) and Chloride (Cl) by mixing a piece(s) of Zinc and 50mL of Hydrochloric Acid (HCl). The amount of Zinc was determined to be between 1.00g and 1.25g. As the reaction occurred there was still water left in the beaker. In order to remove the water we heated the beaker to evaporate it. The Zinc Chloride then formed as a solid white substance. * Observations
As the Zinc and Hydrochloric Acid reacted, bubbling and fizzing occurred. The water became cloudy as the Zinc began to decompose and break apart. The Hydrogen in the Hydrochloric Acid was being released as vapors. * Data & Evaluation
The mass of our beaker was 58.78g. Our piece of Zinc was massed at 1.24g. Therefore, the combined mass of the beaker and Zinc was 60.02g. After the reaction and heating, the combined mass of the Zinc Chloride and the beaker was 61.39g. We heated the substance again to remove any excess water. The combined mass of the beaker and Zinc Chloride was then 61.36g. To find the mass of the reacted Zinc Chloride we subtracted the mass of the beaker (58.78g) from the total and the mass of the Zinc Chloride came out to be 2.58g. Subtracting the mass of the Zinc (1.24g) from the Zinc Chloride mass, we found the mass of just the Chloride was 1.34g. * Conclusion
To find the Empirical formula we first needed to find the number of moles of each element per the mass of each element. You must divide the obtained mass of an element by the atomic weight of that element.
1.24g Zn ×1 mol Zn65.4g Zn= .018 mol Zn
65.4g represents the atomic weight of the Zinc on the periodic table
1.34g Cl ×1 mol Cl35.5g Cl= .037 mol Cl
.018 mol Zn.018 mol Zn=1