Positive Benedict's test without heat

[ThisIsDarwin]

Could a positive Benedict's test for glucose be possible without heating it if left for an extended period of time (72+hrs) at room temperature?

 

Thanks!

[John Cuthber]

Probably.
Try it and find out.

[jimmydasaint]

As the Benedict's Test is for monosaccharides and maltose ( a disaccharide), I would have thought that heat would be needed to thermodynamically favour the linear form of the sugar which is able to reduce the Cu++ ion in the Benedict's reagent to Cu+ causing the colour change from blue to brick-red. The mechanism seems to be as follows (with the sugar in the aldose form instead of the ring form and then oxidised into a carboxylic acid with the simultaneous reduction of Cu++ to Cu+)):

http://laboratoryinfo.com/benedicts-test-principle-reagent-preparation-procedure-interpretation/

If it is true that heat is needed to open up the closed ring structure of monosaccharides, the reaction might not take place at room temperature. I am not sure about this point. 

 

Edited October 29, 2017 by jimmydasaint

[John Cuthber]

It's also possible for things that are not glucose to give a positive result.

I think vitamin C will reduce  Benedict's solution.