Berry Event No. 3 – Effective Chemistry Practical Course Johor 2010 (Kursus Amali Berkesan Kimia Johor 2010) – Johor Bahru : Jabatan Pendidikan Negeri Johor

by BerryBerryTeacher

in Berry Event

Ever wondered how teachers get so adept at conducting experiments in schools? Actually teachers are always sent for trainings to improve the quality and effectiveness of their teaching standards.So this post (Berry Event No.3) is exactly about one of the training sessions for teachers, and in this case about how teachers getting their hands dirty on various experiments to ‘upgrade’ their chemistry practical skills. Berry Readers who are interested in the unseen aspect of a teacher’s life are invited to have a peek on the inner workings of the teaching profession.

(Tips for Teachers and Lab Assistants: There are two experiments shown below which should be conducted for students. They include techniques not written in textbooks.)

Berry Event #3 – Effective Chemistry Practical Course Johor 2010 (Kursus Amali Berkesan Kimia Johor 2010) – Johor Bahru :  Jabatan Pendidikan Negeri Johor

  • Event: Effective Chemistry Practical Course Johor 2010 (Teknik  Amali Berkesan Kimia 2010) Secondary School – Form 4 and 5
  • Date: 22nd July 2010
  • Venue: Sekolah Menengah Teknik Johor Bahru, Johor Bahru
  • Target: Chemistry Teachers in Johor Bahru District
  • Event Covered by: Miss Isabelle Wong – The Berry Berry Teacher – Chemistry Teacher
  • Speaker: Sheikh Kamal (SM Teknik Johor Bahru, Johor), Lee Wai Siew (SMK Tunku Abdul Rahman Putra, Kulaijaya), Faridah Bte Abdir Kadir (SMK Sultan Ismail, Johor Bahru), Md Sihat Bin Md Amin (SM Teknik Johor Bahru)
  • Dedicated to: The dedicated Chemistry Teachers (Guru Cemerlang) in Johor and Laboratory Assistants of SM Teknik Johor Bahru.
There were about 40 teachers who participated this Effective Chemistry Practical Course from 8 a.m. until 5 p.m. . All the teachers were divided into two groups. Teachers got to do at least 10 hands-on experiments in the laboratory within 4 sessions. Chemistry teachers from Johor Bahru district got a chance to expose themselves in the teaching and learning of effective techniques in preparing, conducting, the proper methods and tips of the experiments or science activities. In this event, I would like to share out two important and distinct experiments that Chemistry Teachers should carry them out in the laboratory.

Berry Berry Teacher carried out experiments in Chemistry Laboratory

Berry Berry Teacher carried out experiments in Chemistry Laboratory


Experiment 1 - Form 5 Chapter 3: Redox Reaction – Oxidation & Reduction Effect of Other Metals on the Rusting Of Iron

There is a very effective way in preparing this experiment which can make this experiment interesting and can get effective results in a short time, so all teachers and laboratory assistants must try this out! This method is recommended by Md Sihat Bin Md Amin (Sekolah Menengah Teknik Johor Bahru).

Teachers need to briefly give explanations to students as they should be given some background/pre-knowledge of this experiment. It will help the students to understand the concept of rusting or corrosion better.

Problem 1: How to make the iron nail to rust in the fastest rate and at the same time get to observe the result within a day?

Tips: All the nails must be dipped in concentrated acid for few hours (at least 30 minutes) before the experiment start. Example: hydrochloric acid. This method will remove the antirust coated on the surface of the iron nails. (This method is not stated in any of the textbook, so teachers and laboratory assistants need to take notes!)

Figure 1: All the nails are soaked in the acid before state the experiment. Then clean them with sand paper.

Figure 1: All the nails are soaked in the acid before state the experiment. Proceed to clean them with sand paper.

Problem 2: How to coil these nails to get the best results?

Tips: There must be some ‘gap’ when coiling the metal on the nail. So the changes of colouration can be seen clearly when the iron nail is contacted with the metal.

Figure 2: All these nails were badly coiled with the metal. There must be some ‘gap’ (space) in between.

Figure 2: All these nails were badly coiled with the metal. There must be some ‘gap’ (space) in between.

There must be a gap for the corrosion to take place.

Figure 3: Metal strips cut into a smaller strips. There must have some space in between. All the iron nails were being coiled with gap in between, therefore students can observe the corrosion result easily.

Figure 3: Metal strips cut into a smaller strips. There must have some space in between. All the iron nails were being coiled with gap in between, therefore students can observe the corrosion result easily.

Problem 3: How to view the result clearly?

Tips: Drop few (2 – 4) drops of potassium hexacyanoferrate(III) solution into the hot jelly but not too much! You cannot get good observation if it is too yellowish.

Figure 4: Too much potassium hexacyanoferrate(III) solution which make the jelly too yellowish (left and right test tube) and there were air bubble present in the jelly (left test tube).  This can inhibit the students to from getting good results and confuse the students.

Figure 4: Too much potassium hexacyanoferrate(III) solution which make the jelly too yellowish (left and right test tube) and there were air bubble present in the jelly (left test tube). This can inhibit the students to from getting good results and confuse the students.

Make sure there is no air bubble trapped in between the iron nail and metal strip. It will effect the results. Therefore, pour the hot jelly slowly into the test tubes.

Figure 5: Try to use normal jelly strip (agar-agar) from the market. This will help the students to get clearer observation.

Figure 5: Try to use normal jelly strip (agar-agar) from the market. This will help the students to get clearer observation.

About 10 -20 small strips of agar-agar soak in 100 cm3 of distilled water. And only few drops of potassium hexacyanoferrate(III) solution and phenolphthalein solution are added into the hot jelly.

Figure 6: Very bad results and the students cannot make any observation.

Figure 6: Example of very bad results which do not allow students to make any observation.

Do not add too much potassium hexacyanoferrate(III) solution.

Figure 7: Iron nail + magnesium: After 1 hour to two hours, pink colouration (phenolphthalein solution) was present with very high intensity. Iron(II) ions did not present. The iron nail did not rust.

Figure 7: Iron nail + magnesium: After 1 hour to two hours, pink colouration (phenolphthalein solution) was present in very high intensity. Iron(II) ions not present. The iron nails dd not rust.

Pink colouration can be seen clearly in Figure 7.

Figure 8: Iron nail + copper: After 1 hour to two hours, blue colouration (potassium hexacyanoferrate(III) solution) was present with very high intensity. Iron(II) ions present. The iron nail rusted very quickly.

Figure 8: Iron nail + copper: After 1 hour to two hours, blue colouration (potassium hexacyanoferrate(III) solution) was present in very high intensity. Iron(II) ions present. The iron nail rusted very quickly.

Blue colouration can be seen clearly in Figure 8.

Problem 4: How to make students to understand this concept in a short time and not to confuse them?

Tips: Time management is extremely important for a teacher. This can be done when teachers prepare a set of result three days beforehand for the students to compare their result. Students need to know what is the relationship between the colouration and the ions present in the jelly before the start of the experiment. Teachers also need to carry out a discussion session with students after the experiment and identify students’ misconceptions towards this activity.

Summary of the results and observation:

Test tube Pair of metals Intensity of dark blue colouration Intensity of pink colouration Inference regarding rusting
I Fe only Low None Iron(II) ions present. The iron nail rusts a little.
II Fe + Mg None Very high Iron(II) ions not present. The iron nail does not rust.
III Fe + Cu Very high None Iron(II) ions present. The iron nail rusts very quickly.
IV Fe + Zn None High Iron(II) ions not present. The iron nail does not rust.
V Fe + Pb High None Iron(II) ions present. The iron nail rusts quickly.

Discussion:

In rusting process, iron(II) ions are produced. These ions form blue colouration with potassium hexacyanoferrate(III) solution.

During the corrosion of metal, the reduction of oxygen forms hydroxide ions, thus it gave rise to alkaline condition. The hydroxide ions give pink colouration with phenolphthalein.

Experiment 2 – Form 4 Chapter 8: Constructing Ionic Equation Using Continuous Variation Method

In this experiment,it  is very important for the students to calculating the number of moles of ions in each of the reactant solution and mole ratio of the ions and finally the construction of the ionic equation of the reaction. This method is recommended by MD Sihat Bin Md Amin (SM Teknik Johor Bahru).

Figure 9: L - colourless solution is lead(II) nitrate and R - yellow transparent solution is potassium chromate(VI)

Figure 9: L - colourless solution is lead(II) nitrate and R - yellow transparent solution is potassium chromate(VI)

Problem 1: How to get a constant precipitation formation in test tube 6 and test tube 7.

Tips: Shake thoroughly with a stopper after volume of lead(II) nitrate and volume of potassium chromate(VI) is added. After that, the test tubes are left aside. Use same size of test tube.

Test tube 1 2 3 4 5 6 7
Volume of lead(II) nitrate (cm3) 5.00 5.00 5.00 5.00 5.00 5.00 5.00
Volume of potassium chromate(VI) (cm3) 1.00 2.00 3.00 4.00 5.00 6.00 7.00
Figure 10: (R-L: Test tube 1, 2, 3 ... 7). Yellow aqueous solution was presented in test tube 6 and test tube 7. It was because of the presence of CrO42- ions were excess.

Figure 10: (R-L: Test tube 1, 2, 3 ... 7). Yellow aqueous solution was presented in test tube 6 and test tube 7. It was because of the presence of CrO42- ions were excess.

Make sure students do not shake the test tube after the formation of the yellow precipitate.

So there you go, the life of a teacher unseen from the perspective of a student/parent. To be honest, it’s an enriching exercise to be learning from experts who taught us the minute details of conducting experiments. This allows us to transfer our acquired knowledge to our students. Do write to back or drop comments at Berry Berry Easy if you have anything similar to share.

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