CHEM E CARS
Reactics Bathara is a Chem-E-Car with the dimension of 15 x 20 cm and less than 1.5 kg weight. With safety as the priority, this car is made of acrylic, which is corrosive resistant. Reactics Bathara is divided into some parts, stopping, power source, and other components, such as dynamo, electrical current, and extra load. This car has also been declared safe from design aspect and calculation by a program.
The power source of Reactics Bathara is gotten from a simple reaction between aluminum plate and potassium permanganate. This reaction turns on wet battery function without producing harmful waste. Two parallel battery that consists of six cells, each are installed to optimize power. Two amperes and twelve volts are produced from the car. The overall reactions are shown below.
Al(s) + MnO4– (aq) + 2H2O(aq) à 2Al(OH)4–(aq) + MnO2(s)
2Al(s) + 6H2O(l) + 2OH–(aq) à 2Al(OH)4– (aq) + 3H2(g)
Even though the reaction is using potassium permanganate, it is considered safe due to small concentration, harmful potential has been calculated and handled.
Reactics Bathara is using Vinegar Clock Reaction as stopping mechanism, this stopping mechanism is similar to Iodine Clock Reaction but the materials are food grade and can be found easily in the market. The colour of the solution is changing from transparent to black due to the change of concentration and time. When the solution turns to complete black, the light sensor will automatically cut the electrical current to stop the car.
Flimo is a third generation gas car with 0.1 HP. With the dimension of 20 x 30 x 12 cm and weight of 1.5 kg, Flimo is the smallest and lightest in its class. This car is designed to reach maximum distance of 15 m. The distance is going to be reached with the reaction of yeast and hydrogen peroxide. Yeast is relatively safe for health and usually used in making bread. Hydrogen peroxide is a reactive chemical substance that easily decomposed into water and oxygen. Both of the reaction will give oxygen, a chemical substance fundamental for life. Flimo starts the reaction between twelve grams of yeast and 5% hydrogen peroxide with certain volume that occurs in a vessel. The reaction is shown below.
2𝐻2𝑂2 (𝑎𝑞) + 𝑌𝑒𝑎𝑠t(𝑎𝑞) → 𝑂2(𝑔) + 𝐻2𝑂(𝑙) + 𝑌𝑒𝑎𝑠𝑡(𝑎𝑞)
Produced oxygen is held in the vessel that gives pressure and will be channeled to the regulator. The regulator will hold the pressured oxygen until the wanted pressure reached. Then, pressured oxygen will be released to pneumatic and move the gears that start the car. Stopping mechanism for this car uses buffer reaction. Buffer reaction occurs when one of the reactants runs out and the reaction will stop producing oxygen. The pressure in the vessel is dropping simultaneously and when there’s not enough pressure to move the pneumatic, the car stops.
Flimo consists of vessel, pneumatic, and frame. This car can produce torque of 3 Nm on 5 rpm and maintaining the car speed also can reach maximum 0.5 m/s with regulator pressure at 30 psig. Flimo vessel’s is made from stainless steel with 1.5 mm thickness. This vessel has 90 cc volume and designed to handle pressure until 230 psig and also equipped with safety valve and 150 psig pressure gauge. The pneumatic system is consist of regulator to control the maximum pressure to reach 90 psig, in/out controller to control reciprocate pneumatic, and pneumatic to move the wheels. Flimo’s frame is made from acrylic that can withstand up to 3 kg loads. The frame is combined with acrylic wheel frame to balance the car
The need for efficient alternative energy has led to the discovery of cars with pressurized gas energy sources. A shoe box sized car named Sembrani uses high pressure oxygen to move. Oxygen is a product from the decomposition reaction of hydogren peroxide (H2O2) with Iron (III) Sulfate (FeSO4) as the catalyst, with the following reaction:
H2O2 (aq) → O2(g) + H2O(l)
From literature studies, the usage of FeSO4 as a catalyst will give a faster rate of reaction compared to the existing catalysts. The process of hydrogen peroxide decomposition itself does not produce a hazardous product, so it is safe for the environment.
Made from acrylic as the chassis, Sembrani is equipped with vessel as the reactor. Once the reaction occurs, oxygen gas will be produced and the pressure inside the reactor will increase. By opening the faucet, the gas produced from the reaction will enter the water trap, so that only oxygen will enter the solenoid and moves pneumatic. Reciprocating motion from the pneumatic is converted into rotational motion by the presence of crankshaft, which then moves the wheels of the car.
This car does not have the stopping mechanism. Once the reaction runs, the car will start running and will stop when the existing pressurized oxygen runs out.
Since this car is operated with high pressure gas and exothermic reaction, for the safety reason the vessel has been designed in such a way, and equipped with safety valve and isolator.
Gatotkaca 1.0 is a Chem-E-Car that applied the concept of Volta Cell as the main energy source. This car’s dimension is 30 x 25 cm. without extra load, this car is 1.2 kg weight. Gatotkaca 1.0 is made from anti-corrosive, light, and long lasting acrylic. This car has three parts, stopping, main energy source, and other components, such as dynamo. Dynamo is chosen with considering torque and car weight to achieve accurate distance. Gatotkaca 1.0 uses tensioner to make sure it goes straight.
This car main energy source is gotten from redox reaction between aluminum plate and hydrogen peroxide. This reaction is called Al-H2O2 battery. Materials that were used to make this cell are aluminum plates, hydrogen peroxide, sodium hydroxide, stainless steel, and copper plate. These materials are easy to get and not producing dangerous waste. Aluminum plate works as the anode and hydrogen peroxide as the cathode. Sodium hydroxide as electrolyte. The reaction is shown below:
Anode : Al + 4OH– à Al(OH)4– + 3e– Eanode = 2.33V
Cathode : HO2– + H2O + 2e– à 3OH Ecathode = 0.88 V
Overall Reaction : 2Al + 3HO2– + 3H2O à 2Al(OH)4– + OH– Esel = 3.21
The stopping mechanism for this car is using iodine-vinegar clock reaction. The materials are sodium thiosulfate, hydrogen peroxide, vinegar, starch, and potassium iodide. This reaction is quite similar to iodine clock reaction, while iodine-vinegar clock reaction is using vinegar as H+ donor and an iodine clock reaction, sulphuric acid is used as H+ donor. The used of vinegar has some benefits in economics and safety perspective. From economics, vinegar is cheaper, meanwhile from safety, vinegar is also safer from sulphuric acid which is more corrosive. Stopping mechanism happens in a syringe that is located in front of the car. A LED will light through the syringe and the light will reach a photoresistor. Photoresistor will detects the changes of light intensity. After iodine-vinegar clock reaction is done, the solution will change its colour to black and photoresistor will cut the electrical current to stop the car.