does the concentration of sugar in coke change over time after seal is broken??

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Offline vik_92

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hey i need help with this science project any 1 have a view on this

does the concentration of sugar in coke change over time after seal is broken once??

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Offline vik_92

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anyone have a hypothesis on this [?]

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Offline Chemistry4me

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How much time do you have on your hands to do this project?

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Offline vik_92

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Offline Chemistry4me

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How are you going to test the concentration of sugar?

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Offline vik_92

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i am planning to use a refractometer-brix (sugar)

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Offline vik_92

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what do you think the result of the sugar concentration will be if i get 3 samples of coke and measure the concentration of sugar in each sample in equal lenths of time eg: 1 a week

what will happen 2 the sugar concentration of the samples will the sugar concentration increase,stay the same, or decrease??

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Offline Chemistry4me

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Are you going to keep the lids on or off once the seal is broken?
« Last Edit: 26/04/2009 10:43:17 by Chemistry4me »

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Offline vik_92

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the lids will be off for a 10mins a day

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Offline vik_92

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any one have any other interesting projects i can do involving sugar concentrations

i would luv to have heaps of ideas

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Offline Bored chemist

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You will need good temperature control and a good refractometer to see any change.
I can think of 2 things that would cause a change in the sugar concentration- the water could evaporate giving a rise in concentration or something could remove the sugar causing a decrease. The only thing I can think of that would remove the sugar is fermentation if some yeast somehow got into the cola- but most cola drinks are too acid for yeast to grow well.
That leaves evaporation which isn't going to be a major effect with the lid off for just 10 min.
I'd get another bottle and leave that open for the whole month (under a shelf or something to keep most of the dust out).
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Offline RD

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any one have any other interesting projects i can do involving sugar concentrations

i would luv to have heaps of ideas

You can make colourful pictures with sugar, if you have a polarising microscope with camera attached,
different starting concentrations (before evaporation) will produce different patterns of crystallization.
 
[attachment=8127]

http://www.sciencephoto.com


[attachment=8125]

Quote
Sugar. Polarised light micrograph of crystals of sucrose, also known as cane or beet sugar. It is a sweet, soluble, crystalline carbohydrate composed of linked glucopyranose and fructofuranose units. With dilute acids or invertase it is rapidly hydrolysed to give glucose and fructose. Sucrose sugar is easily digested and forms a major source of energy in humans. It is both a sweetener and a preservative, and is used in cooking and the food industry. A high consumption is associated with obesity and tooth decay. Magnification x10 at 6x7cm size, x5 at 35mm size.
http://www.sciencephoto.com
« Last Edit: 26/04/2009 23:54:30 by RD »

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Offline vik_92

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does anyone think that the ph of coke will change over time?

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Offline Bored chemist

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does anyone think that the ph of coke will change over time?
Yes, but not much.
As the drink loses CO2 it will become slightly less acid and the pH will rise. But the stuff also contains a fair bit of phosphoric acid and that's just going to sit there being acidic.
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Offline chris

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BC - you mentioned yeast getting into the cola and metabolising sugar. I think the same could apply to bacteria too.

Chris
I never forget a face, but in your case I'll make an exception - Groucho Marx