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TGV4:
More flames: propanone
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Notes
on the video of propanone burning
Students should notice that the propanone ignites before the
lighted splint touches the liquid. (You may find it helpful
to pause the video and ‘step’ forward frame by
frame at this point and when the hot wire is used).
It can be ignited by the lighted splint and by the hot wire.
The video makes an important point: the wick is just there
to supply fuel to the reaction site. (This is also stated
in the summary diagram).
Notes on the ‘Think for Yourself’ questions
What do you think the flame is?
A chemical reaction between propanone
and oxygen.
Why does it ignite before the lighted splint or the hot wire
touches the liquid surface?
Some propanone particles have escaped by evaporation, so there
is a mixture of propanone and oxygen molecules above the surface.
Why does the flame keep going?
More propanone evaporates.
Two new substances are formed in the reaction. Predict what
they will be.
Water and carbon dioxide. Hydrogen
atoms from the propanone combine with oxygen atoms from oxygen
to make water. Carbon atoms from the propanone combine with
oxygen atoms from oxygen to make carbon dioxide.
Does the oxygen atom in each molecule of propanone play any
part in the reaction?
No. It will remain bonded to the
carbon atom in a molecule of carbon dioxide. It is the oxygen
atoms of the substance oxygen that take part in the reaction.
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Science Enhancement Programme CD-ROM 2005 |
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