A Chemical Test-Drive: Fun with Chem-E Cars

Wilson, eNotes’ Math and Science intern, shares his experiences of creating a car from scratch and racing it in a statewide contest. Science nerds, prepare to freak out!

The day finally came. After hours and hours of testing, we were finally ready to have our miniature car compete with those of 10 other California universities, including Stanford, UC Davis, UC Berkeley, and San Jose State, at the Chem-E (Chemical Engineering) Car competition hosted over the weekend at UC San Diego.

The requirements were that this car should be relatively light, be powered by a chemical reaction of our choice, be able to have a time-dependent braking mechanism, and be able to carry a certain amount of weight (water) across a certain distance in under 2 minutes.

Our β€œBruin Car” ran off of an electric motor powered by a hydrogen fuel cell, which was supplied hydrogen using a chemical reaction between hydrochloric acid and magnesium. The braking mechanism was an iodine clock reaction that would interfere with the transmittance of light onto the photoresistor in our circuit; thus, when the solution turned completely dark, the photoresistor’s resistance would increase, causing the current to drop and cut off the source of electricity to our electric motor.


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