Redox reaction, changing a solution from yellow to blue

In summary, the conversation revolved around an experiment where an unknown yellow solution turned dark blue when shaken due to a redox reaction. Glucose acted as the reducing agent while NaOH acted as the oxidizing agent. Methylene blue was present to speed up the reaction and the shaking increased the presence of oxygen, further speeding up the reaction. The individual also mentioned finding information on methylene blue and the blue bottle reaction on Google.
  • #1
future_vet
169
0
Hello,

Today, we saw an experiment where an unknown yellow solution became dark blue while it was being shaken.

I have an explanation for it, but would like your opinion as well:

We had a redox reaction, with the oxidation of glucose (being the reducing agent) by NaOH (being the oxidizing agent). The solution had methylene blue to speed up the reaction, causing the liquid to become blue upon shaking (the shaking increased the presence of oxygen, also speeding up the reaction).

Would that be a good answer, or am I missing something?

Thank you,

J.
 
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  • #3
Thank you!
 

1. What is a redox reaction?

A redox reaction, short for reduction-oxidation reaction, is a chemical reaction in which there is a transfer of electrons between the reactants. This transfer of electrons results in the oxidation of one substance and the reduction of another.

2. How does a redox reaction change a solution from yellow to blue?

In a redox reaction, a substance that is being oxidized loses electrons, causing its oxidation state to increase. This change in oxidation state can lead to a change in color of the solution, as different oxidation states can have different colors. For example, the yellow color of a solution may be due to a substance in its reduced form, and when it undergoes oxidation, it may turn blue due to the formation of a new oxidized substance with a different color.

3. What is the role of oxidation and reduction in a redox reaction?

Oxidation and reduction are two key processes in a redox reaction. Oxidation is the loss of electrons, while reduction is the gain of electrons. In a redox reaction, one substance is oxidized while another is reduced, resulting in a transfer of electrons between the two substances.

4. What are some examples of redox reactions that change a solution from yellow to blue?

One example of a redox reaction that can change a solution from yellow to blue is the reaction between potassium permanganate (KMnO4) and hydrogen peroxide (H2O2). In this reaction, the purple KMnO4 solution turns colorless as it is reduced to Mn2+ ions, while the H2O2 is oxidized to O2 gas, causing the solution to turn blue. Another example is the reaction between iodine (I2) and thiosulfate ions (S2O32-), where the initially yellow solution turns blue as the I2 is reduced to I- ions and the S2O32- is oxidized to S4O62- ions.

5. Can redox reactions only change a solution from yellow to blue?

No, redox reactions can result in a variety of color changes in a solution, depending on the substances involved and their oxidation states. For example, a redox reaction between iron (II) ions (Fe2+) and potassium permanganate (KMnO4) can result in a solution that changes from colorless to pink or purple, depending on the concentration of the reactants. Similarly, a reaction between chromium (III) ions (Cr3+) and bromine (Br2) can result in a solution that changes from green to orange. The specific color change will depend on the substances involved and their oxidation states.

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