Pic 1.Preparation.
This pic shows sucrose (table sugar) in its crystallised form being placed in a foil based container about to be exposed to heat from the Bunsen burner.
Pic 2. Melting
This picture shows a physical change- the sugar crystals are melting to form a clear liquid. The melting point of pure sugar occurs between 320 and 321 degrees Fahrenheit. Melting points may vary with impure varieties of sugar. As sugar is heated, the molecules separate, break apart and dissolve. The molecules move away from one another, also known as diffusion. The molecules cool when removed from the heat source, reverting the sugar back to its crystalline form.
Pic 3 Caramelization.
As sugar is heated above its melting point, it begins to brown, also known as caramelizing. This is a sweet syrup that is used to flavour foods. Caramelization occurs during decomposition.
Pic 4 Further Decomposition.
As heating continues, there will be further decomposition to a thick, dark coloured, bitter tasting mixture.
Pic 5.Burning.
At this stage if a flame is held near to the mixture it will burn.
Pic 6.
Continued heating well beyond caramelization will produce carbon contaminated with traces of decomposition products.
References-
pictures- www.chemistryland.com/CHM130FieldLab/Lab4/Lab4.html
Harold Mc Gee On Food and Chemistry
Ramsden, E. (2001) Chemistry
References-
pictures- www.chemistryland.com/CHM130FieldLab/Lab4/Lab4.html
Harold Mc Gee On Food and Chemistry
Ramsden, E. (2001) Chemistry
These illustrations are fantastic Gillian, they really demonstrate the reaction of the molecules when exposed to heat.
ReplyDeleteThanks I do try my best!!!
ReplyDeleteJust realised I didn't put my name to that comment.. But those pictures really do explain clearly the process which sugar molecules go through when heated - Vicky Mitchell
ReplyDeleteForgot to put in but if you want to find out more, these pic came from www.chemistryland.com/CHM130Fieldlab/Lab4/Lab4html
ReplyDeleteI also used Chemisty - Ramsden (2001)