Empirical Formula of Copper (II) Chloride
Gabriella Jane Lukas
Empirical Formula of Copper (II) Chloride
1. To validate that the empirical formula of copper (II) chloride is . 2. To calculate the percent composition of copper in copper (II) chloride. 3. To illustrate the Law of Constant Composition in copper (II) chloride. 4. To study the reaction between copper (II) chloride solution and aluminium metal.
One of the most fundamental statements of the atomic theory is that elements combine in simple whole number ratios. This observation gives support to the theory of atoms, since no one would expect atoms to combine. It is observed that the combining ratio for a given compound is constant regardless of the origin of the pure substance. This is known as the Law of constant composition. The mass contribution of each atom in a compound is a function of the number of atoms in the simplest formula and the relative mass of each atom. The mass contribution is usually referred as the percent composition of a compound (“Determination of”, n.d., p. 1). An empirical formula of a compound provides a number of information. It gives the simplest whole-number ratio between the numbers of atoms of all the elements present in the compound, as well as the names of all the elements present in the compound (“The significance,”, n.d., Significance section, para. 1). In this experiment, the empirical formula of a compound consisting copper and chlorine will be verified as . A known mass of aluminium metal is added to a carefully measured volume of blue solution known to contain a certain amount of copper (II) chloride. As the reaction proceeds, the blue colour of the solution will disappear and a reddish solid of copper metal will appear. Once the reaction is complete, the copper metal is left to dry and weighed together with the excess aluminium. Knowing the original mass of copper (II) chloride present, the empirical formula can be determined.
1. 1. 1 g of copper (II) chloride
2. 2. 60 ml of distilled water
3. Aluminium wire
3. 4. Electronic balance
4. 5. Pasteur pipette
5. 6. Buchner funnel
6. 7. Filter paper
7. 8. Forceps
8. 9. Glass rod
9. 10. Weighing container
10. 11. Watch glass
11. 12. Acetone
14. 1. 1 gram of copper (II) chloride is weighed on an electronic balance using a container. The weight of the solid is recorded. 15. 2. The copper (II) chloride is transferred to a 100 ml beaker and 60 ml of distilled water is added. The contents in the beaker are stirred with a glass rod until the solid is completely dissolved. 16. 3. A handle is made on one end of a 12.5 cm length of aluminium wire, and a flat coil on the other end. The wire is hung at the side of the beaker, immersing the coil in the solution. 17. 4. The wire is shaken when flakes of brown copper are seen accumulating on the wire until the initial blue colour of the copper (II) ions disappear. 18. 5. A vacuum filtration is set up using a Buchner funnel. 19. 6. A filter paper that fits into the funnel is weighed. The weight of the filter paper is recorded. 7. The filter paper is moistened with distilled water and the water aspirator is turned on. 8. The copper is filtered through the Buchner funnel. Finally, the copper is washed in the funnel with 30 ml of acetone. The copper is left on the filter paper for 10 minutes with the water running. 20. 9. Using a pair of forceps, the filter paper is carefully removed from the Buchner funnel. The filter paper and the copper are weighed and recorded. 21. 10. The weight of chlorine is obtained by subtraction.
22. 11. The empirical formula of copper (II) chloride and the error in determining the percentage of copper is determined. 23.
25. Table 1
26. Data for Copper (II) Chloride Analysis
27. Weight of copper (II) chloride
28. 1.01 g
29. Weight of filter paper
30. 0.21 g
31. Weight of watch...
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