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Dehydration of Sugar

Dry Method

Hazards

  • Use care with concentrated sulfuric acid.
  • The fumes given off in this reaction are very irritating.

Chemicals and Solutions

  • 85 g granular sugar
  • 60 mL Sulfuric acid, conc.

Materials

  • disposable 7 oz. poly beaker
  • phototray
  • 100 ml graduated cylinder
  • glass stirring rod

Procedure

Do this demonstration at the end of class so it can be removed immediately.

  1. Measure 85 g sugar into poly beaker.
  2. Add 60 mL concentrated HSO to sugar (After a couple of minutes the sugar turns black and an intense odor of burnt sugar will be noticeable).

Discussion

The reaction:

\( \ce{ C12H22O11 + 11H2SO4 -> 12C + 11H3O+ + 11HSO4- } \)

\( \ce{ C + 2H2SO4 -> CO2 + 2H2O + 2SO2 } \)

Disposal

Remove the demonstration to a hood and allow it to gas off. Once it has finished gassing off send to EH&S labeled as 95% carbon, 5% sulfuric acid.

 

Wet Method

Hazards

  • Use care with concentrated sulfuric acid.
  • The fumes given off in this reaction are very irritating.

Chemicals and Solutions

  • 2 M sucrose solution
  • Sulfuric acid, conc.

Materials

  • 1 - disposable 7 oz. poly beaker
  • 1 - phototray
  • Graduated cylinders, 50 ml and 100 ml

Procedure

Do this demonstration at the end of class so it can be removed immediately.

  1. Measure 50 ml HSO into graduated cylinder.
  2. Measure 60 ml sucrose into 100 ml cylinder.
  3. Combine the sucrose and sulfuric acid carefully in the polybeaker.

Discussion

The reaction:

\( \ce{ C12H22O11 + 11H2SO4 -> 12C + 11H3O+ + 11HSO4- } \)

\( \ce{ C + 2H2SO4 -> CO2 + 2H2O + 2SO2 } \)

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