dehydrating sugar with sulfuric acid

[hermanntrude]

I've been looking at youtube vids again and ive thought of two methods for improving this demo...

 

1) use icing sugar, for better surface area to volume ratio... this should speed the reaction up

 

2) use a conical flask instead of a beaker... this would make the carbon "snake thinner and therefore longer.... i'm not sure if this is safe, thought because if the carbon isnt soft enough it might plug up the neck and make the flask explode? perhaps it's better to use a glass measuring cylinder?

 

what do you think?

 

also... what happens with other carbohydrates? fructose, glucose, starch?

[big314mp]

Would a plastic conical flask work? It might make it safer should it break. Doing it in a closed fume hood would also help.

[Cap'n Refsmmat]

You can throw potassium chlorate into the mixture. It reacts with the sugar as well, making a flaming lump of carbon...

[YT2095]

oddly this is one experiment I have tried many times and never managed to get the same effect that everyone else does?

 

the acid it 98% reagent grade and the sugar is out the kitchen, and yet all I seem to get is a brown/black sludge with little steam

 

needless to say I gave it up after about 4 tries as a waste of good acid.

[hermanntrude]

i think the trick is to use a small quantity of acid... if there's too much then the carbon doesn't solidify and remains slushy

[hydraliskdragon]

oddly this is one experiment I have tried many times and never managed to get the same effect that everyone else does?

 

the acid it 98% reagent grade and the sugar is out the kitchen, and yet all I seem to get is a brown/black sludge with little steam

 

needless to say I gave it up after about 4 tries as a waste of good acid.

 

I've tried dehydrating powder sugar as well but ended up with a not very fast rising pillar of carbon. More like sludge.

 

After some thought, I believed that a catalyze for this dehydration would be needed into speeding up the rate of the reaction as well as producing a copious amount of heat and steam. In remembering that water reacts in a very exothermic reaction with sulfuric acid, I've decided to pour about 5ml of water. Immediately there was a spike in temperature and a black tower of carbon rose fast from the black sludge.

 

Here's a picture of the residual Carbon

 

Here's the video of the reaction.

http://www.youtube.com/watch?v=QPpFt6ePly4&feature=channel_page

[Theophrastus]

Assuming you mean the "black snakes," I find that its generally easier to make a mix of sugar, and baking soda. You then moisten the solution with ethanol, letting the ethanol dry a bit. You then apply a match. The baking soda (sodium bicarbonate) decomposes to produce water (sodium carbonate) and carbon dioxide, this pushes the reaction upwards.

 

2NaHCO3 > Na2CO3 + H2O + CO2

 

The molten sugar does not actively participate, but rather the molten sugar gives it form, as it charrs producing a black snake. Pretty neat. I'ld post pictures, but I have a minor problem with that, as you need to provide a URL. Is there any other way to upload photos? It be rteally useful for further posts.

[hydraliskdragon]

Assuming you mean the "black snakes," I find that its generally easier to make a mix of sugar, and baking soda. You then moisten the solution with ethanol, letting the ethanol dry a bit. You then apply a match. The baking soda (sodium bicarbonate) decomposes to produce water (sodium carbonate) and carbon dioxide, this pushes the reaction upwards.

 

2NaHCO3 > Na2CO3 + H2O + CO2

 

The molten sugar does not actively participate, but rather the molten sugar gives it form, as it charrs producing a black snake. Pretty neat. I'ld post pictures, but I have a minor problem with that, as you need to provide a URL. Is there any other way to upload photos? It be rteally useful for further posts.

 

You can use photobucket for the picture.

 

I am going to try your method since it seems to be very different from this reaction. I'm assuming that it's CO2 trapped bubbles that will raise the reaction upwards?

 

 

By the way, what can I do with the left over carbon?

Edited May 14, 2009 by hydraliskdragon

[Mossydie]

You could try turning it into 12k weave bike parts and selling it at extortionate prices :|