Blue bottle experiment

The blue bottle experiment is a chemical reaction. An aqueous solution containing glucose, sodium hydroxide, methylene blue and some air is shaken in a closed bottle; it turns from colorless to blue and then decolorizes again after a while. With further shaking, the cycle can be repeated many times. This experiment is a classic chemistry demonstration and can be used in laboratory courses as a general chemistry experiment to study chemical kinetics and reaction mechanism. The reaction also works with other reducing agents besides glucose and other redox indicator dyes besides methylene blue.Chemical traffic light reaction time-lapseChemical traffic light reaction (yellow)Chemical traffic light reaction (red)Chemical traffic light reaction (green)solution turn from colorless to redreduced color of the experimentoxidized color of the experimentPattern Formation from Blue Bottle Experiment in Ice Water Bath Time-lapsePattern Formation from Blue Bottle Experiment in Ice Water BathPattern Formation from Blue Bottle Experiment in Cold Water Bath Time-lapsePattern Formation from Blue Bottle Experiment in Cold WaterPattern Formation from Blue Bottle Experiment in Room Temperature Time-lapsePattern Formation from Blue Bottle Experiment in Room TemperaturePattern Formation from Blue Bottle Experiment in Warm Water Bath Time-lapsePattern Formation from Blue Bottle Experiment in Warm Water BathChemical Traffic Light Experiment Pattern Formation In Different Shape Containers Time-lapseChemical Traffic Light Experiment Pattern Formation In Different Shape Containers The blue bottle experiment is a chemical reaction. An aqueous solution containing glucose, sodium hydroxide, methylene blue and some air is shaken in a closed bottle; it turns from colorless to blue and then decolorizes again after a while. With further shaking, the cycle can be repeated many times. This experiment is a classic chemistry demonstration and can be used in laboratory courses as a general chemistry experiment to study chemical kinetics and reaction mechanism. The reaction also works with other reducing agents besides glucose and other redox indicator dyes besides methylene blue. The basic chemistry that is involved in the blue bottle experiment requires understanding the rates and mechanisms of chemical reactions. Concentration and temperature often have effects toward the rate, affecting the reactants and products. While for mechanisms, various of them are able to occur, having different rates. In most cases, the rate of the fastest single mechanisms are selected; however, not all mechanisms happen and end in one step. These mechanisms are known as predominating mechanism where the reaction would then form intermediate molecules which would then react in other processes to form the end product. The rate of predominating mechanisms are calculated by using the rate of the slowest step of the reaction which relies on the temperature as previously mentioned. In addition, intermediate products concentration are usually in a stable state as a result from the fact that they are highly reactive, allowing only small parts of them to endure. Equilibrium state requires that all reaction forward and backward mechanism happens at the same rate. Thus, the net reaction is calculated by the sum of all mechanism steps where the rate depends on the concentration and temperature. The blue bottle experiment relates to the chemistry above because as the bottle is shaken, the kinetic energy as well as the temperature is increased, turning the solution blue. Similarly, as the bottle cools down, the color would then become colorless. The blue bottle experiment originated from using three stock solutions which were potassium hydroxide dissolved in water, added by dextrose after the temperature cools down, and lastly add diluted methylene blue solution. After all the components are prepared, shaking the flask would turn the color of the solvent to turn blue. While leaving it stand turns it colorless. This occurs because alkaline dextrose solution had reduced methylene blue. As the flask is shaken, air which contains oxygen had oxidized the reduction product into blue dye again. Another method that had been developed consists of methylene blue in water, glucose, and caustic soda (which NaOH or KOH could be used instead).In the past, it was understood that the reaction occurred by the oxidation of an aldehyde group to a carboxylic acid under alkaline conditions. For instance, glucose has been oxidized to gluconate by oxygen. However, the experiment also works for compounds such as vitamin C and benzoin, which do not contain an aldehyde. The reaction is actually the oxidation of an acyloin or related α-hydroxy-carbonyl group, which is a feature of glucose, to a 1,2 diketone. The reduced redox dye (colorless state) is formed from oxidised redox dye (blue). These reactions that occur in the blue bottle experiment are also known as clock reaction which originates from an alarm clock. Changes in concentration turns the alarm clock on and off. Limiting reactant, oxygen, are consumed by other reactant which is the benzoin with the help of safranin as a catalyst. Since there is a limited amount of oxygen, when all of it has been used, the catalyst is unable to change forms. As a result, the color of the solution changes its color. The aqueous solution in the classical reaction contains glucose, sodium hydroxide and methylene blue. In the first step the acyloin of glucose is formed. The next step is a redox reaction of the acyloin with methylene blue. The glucose is oxidized to diketone in alkaline solution which is a basic condition. Methylene blue is reduced to colorless leucomethylene blue. The process can be described by as a pseudo first order reaction, using it as an example to understand the changing concentration of the chemicals over the course of the solution going from blue back to colorless. If there is enough available oxygen, leucomethylene blue is then re-oxidized to methylene blue and the blue color of the solution is restored. The availability of oxygen is increased by shaking the solution. When the solution comes to rest, glucose reduction of the redox dye again takes the upper hand and the color of the solution disappears. The reaction is first order in glucose, methylene blue and hydroxide ion and zero-order in oxygen. Other glucose oxidation products besides sodium gluconate that are reported are D-arabino-hexos-2-ulose (glucosone), the anion of D-arabinonate after splitting of a formate anion and finally arabinonic acid. Wellman and Noble proposed a new formulation for the Blue Bottle experiment, vitamin C is used instead of glucose, while methylene blue and oxygen are still used. Copper is added as a catalyst for the reoxidation of leucomethylene blue to methylene blue. These modifications give an experiment that generates a smaller amount of waste that is less corrosive and easier to neutralize, and therefore is an example of green chemistry modification. The Chen autoxidation of benzoin had performed a similar experiment with respect to the classical and green versions. It was found that the traffic light and vanishing valentine experiments can become successful regardless of whether a sugar is added. One variation is more rapid, with the number of color change cycles not lasting as long as the classical and green versions because the reactants are used in smaller amounts; also, the reducing agent for this experiment is benzoin, which is added to help increase the number of cycles in the solution. Moreover, the usable period in this experiment is quite short. Although the experiment is prepared overnight, the reducing agent can be added at any time to be able to observe the solution more. Zhang, Tsitkov, and Hess from Columbia Universityproposed an enzymatic version of the 'blue bottle experiment'. They named it the 'green bottle experiment', since the system is colored green and the reagents are safer than classical approaches.The experiment is performed in a clear glass vial containing two common enzymes (glucose oxidase and horseradish peroxidase), glucose, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (abbreviated as ABTS) in PBS buffer. A thin layer of oil is used to block the solution from the air. The solution initially turns green and then turns colorless with the depletion of dissolved oxygen. Shaking the solution introduces fresh oxygen and colors the solution green again until the oxygen is consumed.