Chemistry out of the box

P.S. Kandagal

Today, science education in India faces many challenges. The most basic of these is the absence of labs and scientific tools in schools. The 8th All India School Education Survey (AISES) conducted by NCERT reveals that out of the total 117,257 secondary schools in the country, only 49,278 (42.03%) have a science laboratory (NCERT Report, 2016). Science is learnt through systematic observation, measurement, experimentation, exploration, speculation and theorization. Often, the only tool that a science teacher will have is the textbook. She describes the experiments therein with the help of pictures and even gives away the outcome. Chemistry, especially, is an experimental science that has to be experienced. Once upon a time, you needed large equipment and expensive materials to carry out experiments (which is the reason not many schools have science labs) but not anymore.

The Royal Society of Chemistry-Yusuf Hamied Inspirational Chemistry Programme (RSC-YHICP) was launched in India in 2014 by the Royal Society of Chemistry Cambridge (UK) with the following objectives:

• To equip 8,000 teachers across India with specialist knowledge and skills to deliver exciting and engaging chemistry lessons, and to share their knowledge with their colleagues.
• To provide 1,600 interested students from different backgrounds with places in chemistry camps to motivate and inspire them to reach the necessary standards to study chemistry at the university level.

I have been a teacher developer for the RSC-YH Inspirational Chemistry Programme, and through this programme, I have trained around 2000 secondary school science teachers and visited more than 60 secondary schools across India in the last five years. During my visits and interactions I found that:

• A majority of the science teachers use the rote learning technique for teaching and learning.
• Teachers emphasize more on theory than practical.
• Teachers lack practical skills and are resistant to doing chemistry experiments.
• Schools lack well-equipped science labs.
• Teachers find it difficult to perform chemistry experiments as described in the textbooks due to lack of equipment and chemicals.
• Financial constraints for purchasing chemicals and apparatus.
• Time constraints.

To overcome these challenges, I made an attempt to develop micro-scale chemistry experimental kits using locally available resources. Around 40 curriculum-based, ready-to-use and eco-friendly micro-scale chemistry kits have been developed and these have been tested and proven to be effective in demonstrating chemistry experiments. The chemistry activities mentioned in the secondary school NCERT textbooks have been modified using low cost and no cost materials for effective classroom demonstrations. These micro-scale chemistry experiments use small quantities of chemicals, involve simple equipment, and reduce preparation time and costs. A few examples will help us understand this better. For every experiment (example) below I start with how NCERT science textbooks describe them and follow it with how teachers can demonstrate the same experiments in a simplified yet effective manner using the micro-scale kits.

Expt.1: Extraction of iron
The following figure illustrates the industrial extraction of iron from haematite ore in a blast furnace using coke and limestone.

Expt. 1: Extraction of iron on a matchstick head
The principle involved in the extraction of iron can be effectively demonstrated using the micro-scale kit. The head of a matchstick is dipped in water to make it wet. It is then rolled in sodium carbonate powder, coke powder and ferric oxide powder and put into flame. The matchstick flares and burns half way along its length. The burnt matchstick is allowed to cool for about 30 seconds and powder from the charred part is removed into a small paper boat. When you move a magnet under the paper boat, some of the small particles of iron also move in the paper boat.

Expt. 2: Preparation of sodium hydroxide (NaOH) by the electrolysis of sodium chloride (NaCl) solution
The figure below illustrates the industrial production of NaOH by the electrolysis process.

This experiment is difficult to demonstrate as it involves lot of time to set up the apparatus.

When electricity is passed through an aqueous solution of sodium chloride (brine), it gets electrolyzed to form sodium hydroxide. Chlorine gas is given-off at the anode, and hydrogen at the cathode. Sodium hydroxide solution is formed at the cathode, thereby changing the colour of the phenolphthalein indicator from colourless to pink. The reaction is represented by the chemical equation:
2NaCl_(aq)+2H₂O₍₁₎ -> 2NaOH_(aq)+Cl_2(g)+H_2(g).

Expt. 2: Preparation of sodium hydroxide by the electrolysis of sodium chloride solution
A pinch of sodium chloride (NaCl) crystals is placed in a watch glass. A few ml of rain water (distilled water) are added to dissolve NaCl. To this, a drop of phenolphthalein indicator is added. The graphite electrodes (pencil electrodes) are placed in the solution in such a way that two electrodes do not touch each other. The electrodes are then connected to a battery using crocodile clips and electric current of 9 V is passed through the circuit for a few seconds. Pink colour appears at the anode due to the formation of NaOH.

Expt. 3: Burning of magnesium in air (Redox reaction)
Redox reaction is described with the following example in the NCERT science textbook. Burning of magnesium in air is an example for redox reaction. The following figure shows an arrangement of the apparatus for burning magnesium in air.

The auto ignition temperature of magnesium is 744 K. A candle flame shouldn’t be used for igniting magnesium as the smoke produced by the candle forms a protective layer on the metal. This activity requires LPG Bunsen burner, which is generally not available in most schools.

Expt. 3: Burning of magnesium in air (Redox reaction)
Magnesium ribbon about 1-2 cm long is cleaned and the oxide layer is removed by washing it with dilute hydrochloric acid. A sparkler is lit using a gas lighter and magnesium is held onto the sparkler flame till it catches fire. Magnesium burns with a dazzling white flame and forms a white residue of magnesium oxide which is collected on a paper.

The chemistry of the experiment is as follows:
When magnesium is ignited using a burning sparkler, it undergoes air oxidation and burns with brilliant white light to form magnesium oxide. The reaction is represented by the chemical equation: 2Mg+O₂ -> 2MgO.

Expt. 4: Formation of hydrogen gas by the action of H₂SO₄ on zinc
The experimental setup for the formation of hydrogen by the action of dilute sulphuric acid on zinc is illustrated in the NCERT science textbook as shown in the figure.

Zinc being more electropositive than hydrogen, displaces hydrogen from dilute sulphuric acid and is represented as: Zn+H₂SO₄ -> ZnSO₄ + H₂^

The liberated hydrogen is collected in a test tube by the downward displacement of air. When hydrogen is ignited using a glowing splint, it burns with a pop sound. The pop sound is due to a small explosion caused by the burning of hydrogen. The experimental procedure presented here is time consuming and demands more equipment. Lack of laboratory equipment in schools restricts the demonstration.

Expt. 4: Formation of hydrogen gas by the action of dil. H₂SO₄ on zinc
The action can be performed in a tablet wrapper (blister pack) at micro-scale to avoid explosion of the highly flammable hydrogen gas. A small piece of zinc is placed in the cavity of a tablet wrapper (blister pack). A few drops of dilute sulphuric acid (H₂SO₄) are added to cover the zinc metal. The evolved hydrogen gas is collected in a test tube by the downward displacement of air. A glowing splint is brought near the mouth of the test tube. The hydrogen gas burns with a pop sound.

Most secondary school science teachers in India face difficulty in demonstrating chemistry experiments due to lack of well-equipped labs and time constraints. These micro-scale chemistry kits can be used to perform regular chemistry experiments without any hassles in the classroom. These kits are eco-friendly, provide better safety, reduce preparation time and help teachers demonstrate experiments during classroom teaching, thereby encouraging learning by doing.

If you would like to know more about our RSC-YHIC teachers training programme email us at drpskilk@gmail.com or teacherdevelopers@rsc.org.

References
• Micro-scale experiments retrieved from http:www.rsc.org/learn chemistry/resource/microscale reaction.
• Royal Society of Chemistry (2014), The particle nature of matter, Teacher book.
• The National Microscale Chemistry Center (2002), http://www.microscale.org.
• http://www.rsc.org/learn-chemistry/resource/res00000722/extraction-of-iron-on-a-matchhead.

The author is a teacher developer with the Royal Society of Chemistry and Assistant Professor, Department of Chemistry, SVM Arts, Science and Commerce College Ilkal, Karnataka. He can be reached at drpskilk@gmail.com.