![]() ![]() The unstable peroxyacid ester decomposes, resulting in additional phenol and a cyclic peroxy compound.The hydrogen peroxide oxidizes the phenyl oxalate ester, resulting in a chemical called phenol and an unstable peroxyacid ester.Here's the sequence of events that occur when the two solutions are combined: When the dye molecule returns to the ground state, the excited electrons return to the ground state and energy in the form of light is emitted. When the dye molecule absorbs energy, the energy is used to raise electrons to an excited state. During the reaction, an intermediate is produced which transfers energy to the fluorescent dye molecule. A typical commercial light stick has a thin walled-glass ampule containing hydrogen peroxide solution floating in a solution of a phenyl oxalate ester with a fluorescent dye. The chemical reaction in a light stick usually involves several different steps. At cold temperatures, t he light stick glows less brightly because in a given time period, fewer reactant molecules are colliding with sufficient energy to form the products. In a chemoluminescent reaction such as this one, at elevated temperature, the increased reaction rate can be perceived as increased brightness of the light being given off by the light stick. At reasonably cold temperatures reactions occur but there are fewer effective reactions compared to the system at higher energy. ![]() Because at any temperature in a gas, liquid, or solution, there is a distribution of molecular speeds, some molecules will have sufficient energy that when they collide a reaction will occur. At lower temperatures, there are fewer collisions and most of the collisions that do occur between reactants do not have sufficient energy to form products. At higher temperatures molecular collisions are more likely to have enough energy to form products. This increases the rate of reaction. Raising the temperature of a reaction mixture results in both more frequent and more energetic molecular collisions. Increasing the temperature increases the average kinetic energy of the molecules. This demonstration shows the effect of temperature on reaction rate. ![]()
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