SCH3U Name:
Lab: Mass Relationships in a Chemical Reaction
Purpose:
To determine the mass of copper formed when excess aluminum is allowed to react with a given mass of a copper salt.
Hypothesis: today should come from a calculation
Introduction:
In this experiment, a given mass of copper (II) chloride dihydrate will be dissolved in water. A piece of aluminum will be placed in the solution, and the reaction will be allowed to go to completion.
3 CuCl2•2H2O + 2 Al 3 Cu + 2 AlCl3 + 6 H2O
The mass of copper produced will be measured, and compared to the theoretical mass.
Apparatus and Materials:
250 mL beaker
stirring rod
heat pad
hot plate
watch glass
CuCl2•2H2O
aluminum strip
Procedure:
1. Prepare a data table for recording the mass of the empty beaker, the beaker with the copper salt, and the mass of the beaker and copper.
2. Determine the mass of a clean, dry beaker. To the beaker add approximately 2.00 g (measure to the nearest 0.01 g) of copper (II) chloride dihydrate. Determine the mass of the beaker and contents. Add about 75 mL of water and stir to dissolve the copper compound.
3. Place the aluminum strip into the solution in the beaker.
4. Place the beaker on a hot plate, and heat the solution until it has boiled gently for 5 minutes. Avoid overheating. There may be some foaming during the early stages of the heating. Allow the solution to cool until you can hold it comfortably in your hands.
5. Shake the aluminum strip in the beaker to dislodge the copper. Remove the aluminum strip, being careful to leave the copper in the beaker. Pour the liquid in the beaker into the sink, being careful not to lose any copper. Add 75 mL of water to the beaker. Stir well to wash the copper, and discard the water into the sink, being careful not to lose any copper. Repeat the washing with another 75 mL of water, again being careful not to lose any copper.
6. Cover the beaker with a watch glass, and gently heat the beaker containing the wet copper to drive off the water. When the initial spattering has stopped, remove the watch glass and continue the gentle heating to drive off the last traces of moisture. Do not heat so strongly that the copper begins to turn black.
7. Allow the beaker to cool, and determine the mass of the beaker and copper.
Calculations:
• Determine the mass of copper (II) choride dihydrate that you started with, and the mass of copper that you ended up with.
• Calculate the theoretical mass of copper that should have formed from the original amount of copper (II) chloride dihydrate.
• Calculate the percentage error according to the equation
% Error = x 100%
Discussion:
The usual stuff! Don’t forget to provide an analysis of any qualitative observations, and a thorough error analysis.
THIS IS A FORMAL REPORT:
Chemistry Lab Report Summary
Category / 4 / 3 / 2 / 1 / Level R / 0 / MarkKnowledge & Understanding:
Scientific Method
Introduction: Background information
Thinking and Investigation:
Gathering Evidence and Data
hypotheses, etc
Experimental Design/ Methods
Communication:
Use of Scientific Terminology, Calculations, and Units
Report Format, Organization & Clarity
Graphing and charting
Application:
Discussion
Error Analysis:
Extensions
Conclusions:
Comments: