Can Pure Carbon Substitute for Starch in the Iodine-Water Clock Reaction?

[minus459.67]

I've been teaching my daughter about the elements and am demonstrating the iodine+water+starch="clock" reaction. In an effort to provide accurate and straightforward information I am wondering that since starch is essentially carbon if pure carbon can be substituted for starch or if the starch has some property essential to the outcome of the experiment?

- Thanks

 

[Borek]

since starch is essentially carbon

Starch is not carbon, it is a carbohydrate.

 

[minus459.67]

Starch is not carbon, it is a carbohydrate.

Thanks for the response. We used pure starch and were successful. We learned the carbohydrates in starch were made up of carbon hydrogen and oxygen. My original idea was that since the experiment included water anyways that the hydrogen and oxygen components of the starch carbohydrate wouldn't necessarily be essential. Although I never tested this hypothesis I have doubts it would work.

 

[Borek]

My original idea was that since the experiment included water anyways that the hydrogen and oxygen components of the starch carbohydrate wouldn't necessarily be essential.

They are essential. There is a huge difference between a compound that contains carbon, hydrogen and oxygen, and mixture containing all three elements.

Most (but not all) carbohydrates have formula C_m(H₂O)_n - that is, they look like made of carbon and water, But it doesn't mean they are made this way, it is just a side effect of the valencies of atoms involved.