Blue bottle (chemical reaction)
Encyclopedia
The blue' bottle reaction is a chemical reaction
in which a colorless solution in a closed bottle containing some air turns blue upon shaking and then decolorizes again after a while. After shaking again the blue color returns and this cycle can be repeated several times . This experiment is a classic chemistry demonstration and can be used in laboratory courses as a general chemistry experiment.
The aqueous solution contains glucose
, sodium hydroxide and methylene blue
. Glucose
in an alkaline solution is slowly oxidized by oxygen
from the air in the bottle after a vigorous shake to form gluconic acid
, which, in alkaline solution is in the sodium gluconate
form:
2 CH2OH–CHOH–CHOH–CHOH–CHOH–CHO + O2 --> 2 CH2OH–CHOH–CHOH–CHOH–CHOH–COOH
Methylene blue
acts as an oxidizing agent for glucose, and it is itself reduced to leucomethylene blue and becomes colorless.
If there is enough available oxygen, leucomethylene blue is re-oxidized and the blue color of solution restores. When the solution comes to rest, glucose reduces the methylene blue dye and the color of the solution disappears.
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
in which a colorless solution in a closed bottle containing some air turns blue upon shaking and then decolorizes again after a while. After shaking again the blue color returns and this cycle can be repeated several times . This experiment is a classic chemistry demonstration and can be used in laboratory courses as a general chemistry experiment.
The aqueous solution contains glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
, sodium hydroxide and methylene blue
Methylene blue
Methylene blue is a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl. It has many uses in a range of different fields, such as biology and chemistry. At room temperature it appears as a solid, odorless, dark green powder, that yields a blue solution when dissolved in...
. Glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
in an alkaline solution is slowly oxidized by oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
from the air in the bottle after a vigorous shake to form gluconic acid
Gluconic acid
Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH24COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid....
, which, in alkaline solution is in the sodium gluconate
Sodium gluconate
Sodium gluconate is a compound with formula NaC6H11O7. It is the sodium salt of gluconic acid.It has E number E576....
form:
2 CH2OH–CHOH–CHOH–CHOH–CHOH–CHO + O2 --> 2 CH2OH–CHOH–CHOH–CHOH–CHOH–COOH
Methylene blue
Methylene blue
Methylene blue is a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl. It has many uses in a range of different fields, such as biology and chemistry. At room temperature it appears as a solid, odorless, dark green powder, that yields a blue solution when dissolved in...
acts as an oxidizing agent for glucose, and it is itself reduced to leucomethylene blue and becomes colorless.
If there is enough available oxygen, leucomethylene blue is re-oxidized and the blue color of solution restores. When the solution comes to rest, glucose reduces the methylene blue dye and the color of the solution disappears.