Chemical Formula Lab
Computer
The Determination of a Chemical Formula
1
Second, you will conduct a chemical reaction with the dried sample, which will produce elemental copper. By measuring the mass of copper that forms, you will have the necessary information to determine the moles of copper and chlorine in your sample, and you will be able to establish the proper chemical formula.
OBJECTIVES
• • •
In this experiment, you will
Ev
al
Determine the water of hydration in a copper chloride hydrate sample. Conduct a reaction between a solution of copper chloride and solid aluminum. Use the results of the reaction to determine the mass and moles of Cu and Cl in the reaction. • Calculate the empirical formula of the copper chloride compound. …show more content…
Obtain and wear goggles. 2. Measure and record the mass of a clean, dry crucible without cover. Obtain about 1 g of the unknown copper chloride hydrate and place it in the crucible. Use a spatula to break up any large pieces of the substance by pressing the pieces against the wall of the crucible. Measure and record the mass of the crucible with compound. 3. Set up a ring stand, ring, and clay triangle for heating the sample. Rest the crucible on the clay triangle. Set up a lab burner and ignite the burner away from the crucible. Adjust the burner to get a small flame. 4. Hold the burner in your hand and move the flame slowly back and forth underneath the crucible to gently heat the sample. Do not overheat the compound. Note the color change, from blue-green to brownish, as the water of hydration is driven out of the crystals. When the sample has turned brown, gently heat the crucible for two more minutes. 5. Remove and turn off the burner. Cover the crucible and allow the sample to cool for about ten minutes. 6. Remove the crucible cover and inspect your sample. If you see any blue-green crystals, reheat the sample until the crystals have turned brown. 7. Measure and record the mass of the cool crucible of your copper chloride sample. 8. Transfer the brown solid to a clean and empty 50 mL beaker. Rinse out the crucible with two 8 mL aliquots of distilled water and pour the water into the 50 mL beaker. Gently swirl the beaker to completely dissolve the solid. Note that the color of the solution is green as the copper ions are rehydrated. 9. Measure out about 20 cm of aluminum wire, coil the wire, and place the wire in the beaker of solution so that it is completely immersed in the copper chloride solution. Note that the reaction produces a gas, elemental copper is forming on the surface of the aluminum wire, and the color of the solution is fading. The reaction will take about 30 minutes to complete. 10. When the reaction is done, the solution will be colorless.
The Determination of a Chemical Formula
1
Second, you will conduct a chemical reaction with the dried sample, which will produce elemental copper. By measuring the mass of copper that forms, you will have the necessary information to determine the moles of copper and chlorine in your sample, and you will be able to establish the proper chemical formula.
OBJECTIVES
• • •
In this experiment, you will
Ev
al
Determine the water of hydration in a copper chloride hydrate sample. Conduct a reaction between a solution of copper chloride and solid aluminum. Use the results of the reaction to determine the mass and moles of Cu and Cl in the reaction. • Calculate the empirical formula of the copper chloride compound. …show more content…
Obtain and wear goggles. 2. Measure and record the mass of a clean, dry crucible without cover. Obtain about 1 g of the unknown copper chloride hydrate and place it in the crucible. Use a spatula to break up any large pieces of the substance by pressing the pieces against the wall of the crucible. Measure and record the mass of the crucible with compound. 3. Set up a ring stand, ring, and clay triangle for heating the sample. Rest the crucible on the clay triangle. Set up a lab burner and ignite the burner away from the crucible. Adjust the burner to get a small flame. 4. Hold the burner in your hand and move the flame slowly back and forth underneath the crucible to gently heat the sample. Do not overheat the compound. Note the color change, from blue-green to brownish, as the water of hydration is driven out of the crystals. When the sample has turned brown, gently heat the crucible for two more minutes. 5. Remove and turn off the burner. Cover the crucible and allow the sample to cool for about ten minutes. 6. Remove the crucible cover and inspect your sample. If you see any blue-green crystals, reheat the sample until the crystals have turned brown. 7. Measure and record the mass of the cool crucible of your copper chloride sample. 8. Transfer the brown solid to a clean and empty 50 mL beaker. Rinse out the crucible with two 8 mL aliquots of distilled water and pour the water into the 50 mL beaker. Gently swirl the beaker to completely dissolve the solid. Note that the color of the solution is green as the copper ions are rehydrated. 9. Measure out about 20 cm of aluminum wire, coil the wire, and place the wire in the beaker of solution so that it is completely immersed in the copper chloride solution. Note that the reaction produces a gas, elemental copper is forming on the surface of the aluminum wire, and the color of the solution is fading. The reaction will take about 30 minutes to complete. 10. When the reaction is done, the solution will be colorless.