Curriculum Expectations:
This is a very interesting and educational demonstration prior to starting oxidation reduction reaction. Students will observe the “Can Ripper” experiment which illustrates an oxidation-reduction reaction. Ideally the teacher should do this in class because showing a video will not have the same impact.
LEARNING GOAL
Remove the tab off of a empty clean soda can. With a sharp object scratch the inside of the pop can all the way around in a circle. Pour a solution of copper (II) chloride to a depth up to the scratch and let the can sit for a 30 minutes. Pour out the copper(II) chloride and rinse the can. The can is now ready to be ripped and a student can be asked to rip it or the teacher may rip it.
Demonstration at a Glance: An empty soda can be easily ripped apart.
CONTENT
Students can be asked to ponder over how the can was ripped apart. The teacher can provide the students with all the materials that were used to conduct the experiment. For example, they should be told of the different layers of a pop via the following video.
http://www.youtube.com/watch?v=V4TVDSWuR5E
- F2.2 conduct an inquiry to analyse, in qualitative terms, an oxidation-reduction (redox) reaction [PR, AI, C]
This is a very interesting and educational demonstration prior to starting oxidation reduction reaction. Students will observe the “Can Ripper” experiment which illustrates an oxidation-reduction reaction. Ideally the teacher should do this in class because showing a video will not have the same impact.
LEARNING GOAL
- Students will observe a single replacement reaction: 3CuCl2 (aq) + 2Al (s) > 3AlCl3 (aq) + 3Cu (s)
- This activity will allow students to see the relevance of chemistry. They will be able to reflect on the chemistry that has gone behind a pop can.
- Students will observe a oxidation reduction reaction.
Remove the tab off of a empty clean soda can. With a sharp object scratch the inside of the pop can all the way around in a circle. Pour a solution of copper (II) chloride to a depth up to the scratch and let the can sit for a 30 minutes. Pour out the copper(II) chloride and rinse the can. The can is now ready to be ripped and a student can be asked to rip it or the teacher may rip it.
Demonstration at a Glance: An empty soda can be easily ripped apart.
CONTENT
Students can be asked to ponder over how the can was ripped apart. The teacher can provide the students with all the materials that were used to conduct the experiment. For example, they should be told of the different layers of a pop via the following video.
http://www.youtube.com/watch?v=V4TVDSWuR5E
CONSOLIDATION
Once students have constructed their own ideas the teacher can provide them with the following information which talks about the chemistry behind the can ripper experiment: - The reason the can is scratched on the inside of the can is because soda cans contain a plastic lining which protects the can the acidic soda. The copper chloride solution reacts with the aluminum In the can as follows
- 3CuCl2 (aq) + 2Al (s) > 3AlCl3 (aq) + 3Cu (s)
- After the reaction the aluminum is no longer lining the scratched part of the can and it is held by a thin layer of paint.
Extension
- The multiple layers which go into a pop can are unknown to many people and in the case of the plastic lining of the pop can there are additional experiments that can be done. To see the plastic lining more carefully the fresh soda whose paint has been sanded off can be placed in a strong solution of HCl. The HCl will dissolve the alumimnum leaving the plastic lining un touched. Please note that the can must be filled with water because the reaction between HCl and aluminum gives off heat which can melt the inner plastic lining of the can. This experiment should be done under a fume hood and prepared prior to class.
ADDITIONAL LESSON STARTER IDEAS
There are hundreds of reactions that can be found in the kitchen which illustrate redox reactions. For example, the browning of fruits, such as apples, bananas, pears, and organs when exposed to the oxygen in the air. A good lesson starter would be to bring in an apple and but into pieces and ask students about the chemical processes that are work on the cut up apple. This will allow students to start thinking about the redox reactions.
There are hundreds of reactions that can be found in the kitchen which illustrate redox reactions. For example, the browning of fruits, such as apples, bananas, pears, and organs when exposed to the oxygen in the air. A good lesson starter would be to bring in an apple and but into pieces and ask students about the chemical processes that are work on the cut up apple. This will allow students to start thinking about the redox reactions.
- McGrawhill: Chapter 9 Launch Lab Penny Chemistry, p. 583
- McGrawhill: Inquiry Investigation 9-A Testing Relative Oxidizing and Reducing
- McGrawhill: Strengths of Metal Atoms and Ions, pp. 618-9
- McGrawhill: Inquiry Investigation 9-B Redox Reactions and Balanced Equations, pp. 620-1
Reference