What is the Sulfuric Acid and Sugar Reaction in Chemistry Demonstrations?

[lapo3399]

Hi,

My chem teacher in high school did a demo 2-3 years ago, which I know involved sulfuric acid and either glucose or sucrose. I believe it was an acid-catalysed reaction which demonstrated the instant release of the energy stored in the sugar as opposed to conversion to ATP. Does anyone know what reaction this is, and how it is carried out?

Thanks

 

[Cesium]

This reaction can be performed with either glucose or surcrose (or almost any organic material for that matter). Sulfuric acid is a very strong dehydrating agent, that is, it has a strong affinity for water. It is such a strong dehydrating agent that it "sucks" out the water from the sugar.

The reaction with surcrose is C12H22O11 --> 11H2O + 12C
The sulfuric acid absorbs the water formed and forms a hydrate. The carbon created is in the form of graphite.

 

[ravenprp]

for your question! The reaction you are referring to is known as a dehydration reaction, and it involves the sulfuric acid acting as a catalyst to remove water molecules from the sugar (glucose or sucrose). This process releases energy in the form of heat and also produces a black, carbon-rich substance. This demo is often used to show the exothermic nature of acid-catalyzed reactions and the release of energy from sugars. It is typically carried out by mixing a small amount of sulfuric acid with a small amount of sugar in a test tube, and then heating the mixture over a Bunsen burner or hot plate. The reaction should occur quickly and produce a noticeable amount of heat and the black substance. I hope this helps!