Stopping team produces a clock reaction that changes in transparency or color after a specified time based on our amount of reagent. When the precipitate forms light can no longer pass through the sensor in our car, triggering it to stop. In the past we have used iodine clock and cinnamaldehyde clock.
Cinnamaldehyde Reaction:
This reaction is a double aldol condensation reaction catalyzed by hydroxide. The Dicinnamalacetone product has low solubility in ethanol. As the reaction proceeds the product precipitates out of the solution.
Iodine Clock:
This reaction is a redox reaction meaning that electrons transfer between species. The reaction produces a color change when iodine reacts with starch. As the reaction proceeds the product precipitates out of the solution.