Science for Fun Activities Term 1 Reflections

In Term 1, I visited the “Science for Fun Activities” workshops where we could have hands-on learning. Different experiments were displayed and it was up to us to conduct them. There were 8 activities and I have gained a considerable amount of knowledge from them.
The first experiment was electroplating where we tried plating a paperclip using electric currents to reduce the ions of a piece of copper and coat a paperclip with a thin layer of copper. Electroplating is used for bestowing a property of a material onto another object. Through electroplating, steel parts such as camshafts, crankshafts, and hand tools resists wear better when they are electroplated with chromium. It can also be used to increase the thickness of an object. In this method, plating is restricted to only conductive objects. An electrolyte is any substance containing free ions that make the substance electrically conductive.The diagram below shows a setup used during electroplating.
Courtesy of: http://www.mems-exchange.org/MEMS/processes/deposition.html
The second experiment was called “Chemical Garden” which is hugely popular with young kids. This experiment has been made into a popular product “Magic Rocks”, which is easy to carry out. This is similar to crystal growing, except that it takes a shorter time, in a matter of seconds. Firstly, sodium silicate is placed in to a container. Next, metal salts such as calcium chloride are added to the sodium silicate solution. Sodium silicate then reacts with the metal salts to form crystal towers of different colours. By changing the type of metal salt, the colour of the crystal tower will differ. This works on the same concept of changing the colour of fireworks by using different chemicals. The chemicals that form different colours are listed belowe.
• White - calcium chloride (found on the laundry aisle of some stores)
• White - lead (II) nitrate • Purple - manganese (II) chloride
• Blue - copper (II) sulfate (common chemistry lab chemical, also used for aquaria and as an algicide for pools)
• Red - cobalt (II) chloride
• Pink - manganese (II) chloride
• Orange - iron (III) chloride• Yellow - iron (III) chloride
• Green - nickel (II) nitrate
The third experiment was about a Cartesian diver where a pen top floats in a bottle of water. The picture below shows a picture of it.
Courtesy of Wikipedia
When the bottle is squeezed, the “diver”, which is the pen top, sinks. When the grip on the bottle is relaxed, the “diver” floats. There is a scientific explanation for this. A bubble is trapped in the pen top, making it less dense, thus it floats. When squeezed, the pressure causes the bubble to get smaller, making the pen top denser, thus, it sinks. When the grip on the bottle is relaxed, the bubble expands and the “diver” rises again.
The fourth experiment was titled “Caught Red-Handed”. This experiment utilizes turmeric paper. When our hands are soaked into baking soda solution and touches turmeric powder, it turns red. This is because when the baking soda solution comes in contact with turmeric paper, the turmeric changes in molecular structure. The change in structure causes it to absorb light at different wavelengths, making it look red. This is used for pH indicators and also explains why leaves turn red or purple in autumn.The fifth experiment was entitled “Chain Reaction”. It involved using different chemicals to create reactions one after another. Firstly, we added 1ml of starch solution to 4 drops of phenolphthalein. Secondly, we added 1ml of sodium hydroxide solution to the solution in the first step. They reacted and turned pink. This is due to alkaline solution added to phenolphthalein indicator which caused a chemical reaction. Thirdly, we added 1ml of hydrochloric acid to the solution in the second step. The solution turned colourless. Fourthly, we added 1ml of sodium bicarbonate solution to the solution in the third step. We observed bubbles forming in the solution. This is because of the left-over acid reacting with sodium bicarbonate produced carbon dioxide. Fifthly, we added 1ml of iodine solution to the solution in the fourth step and the colour of the complex formed when starch reacted with iodine was bluish-black. Finally, we added Vitamin C and the complex turns colourless again. Vitamin C reduces iodine to iodine, turning it colourless again. This is due to the oxidation-reduction reaction.The sixth experiment was about colour changing milk where drops of food colouring were added to the milk and they move. This is the principle behind the use of detergent as a grease remover. Detergents are made up of petrochemicals, oxidizers and alkalis. Petrochemicals are fats or oils which are attracted to the grease. Oxidizers are used to produce hydrophilic component of detergents while alkalis are used to promote chemical reactions. These work together to remove grease.The seventh experiment is about extracting the DNA of a banana. Through this experiment, I learnt that DNA or deoxynucleic acid is what makes up or chromosomes, while chromosomes make up our genes, which affects hereditary traits and how our body functions. We have about 3 billion base pairs of DNA in the 46 chromosomes per cell. The length of 1 base pair is 0.34nm and the total length of DNA from a human cell is about 2m. Assuming we have 1013 cells that make up our body, the total length of DNA in our body is equivalent to about 70 trips from the earth to the Sun and back! To extract DNA from a banana, we require mashed banana, a test tube containing strong detergent, a test tube containing ice cold ethyl alcohol, an empty test tube, one doubled piece of cheese cloth or gauze and a plastic funnel. First, we have to mix the mashed banana with strong detergent. Then, we have to collect the liquid from the banana with a funnel and cheese cloth. Lastly, we have to add ice cold ethyl alcohol. A white string or blob would start to appear from the mixture. This is DNA.
The last activity was about Bernoulli’s principle. From experiments conducted in the eighteenth century, the Swiss mathematician Daniel Bernoulli determined that for a fluid in motion, pressure and velocity are inversely related: pressure is greatest when speed is lowest, and vice versa. By applying Bernoulli's principle, aeronautic engineers have been able to design airplane wings that can carry heavy jets. The top surface of the wing is curved and the lower surface is flat, and as a result, the air rushing over the wing, which has a longer distance to travel, has a greater velocity than the air passing under the wing. Because pressure is greatest where velocity is least, the pressure pushing up on the wing from below is greater than that pushing down from above. The difference in pressure provides a net upward force, called lift, on the wing. In this activity, we demonstrated Bernoulli’s principle using hair dryers. The air blown up from a hair dryer has enough volume and velocity to counter the downward force of gravity acting on two ping pong balls. Because of the fairly random molecular movement of fluids, the balls don't stay still. But unless the airflow is interrupted, they also don't fly away. If a ball drifts away from the center, it constantly adjusts itself to be back in the center. This is because the air around the center column of fast-moving air is moving more slowly and therefore has a greater pressure. When the ball drifts outside the center of the air column and into a region where the air is moving more slowly, the greater pressure in that region pushes the ball back into the fast-moving air column.
This ends off my reflection on the “Science for Fun” activities. I hope I would receive another chance to participate in this workshop again.