Phlogiston vs oxygen
| National Curriculum links
(Key Stage 3) |
Sc1
1a |
... interplay between empirical
questions, evidence and scientific explanations using historical … examples |
Sc1
1c |
... ways in which scientists
worked in the past, including the role of experimentation, evidence
and creative thought in the development of scientific ideas |
Sc3
1e |
... elements combine through
chemical reactions to form compounds |
Sc3
2g |
... mass is conserved when
chemical reactions take place |
Sc3
3a |
... metals react with oxygen
... |
Resources
The Phlogiston Theory
provides a brief guide to the development of the phlogiston theory,
what it was and how it explained observable facts at the time.
Joseph Priestley - a lucky
dabbler looks at Priestley and the way he investigated all sorts
of things out of sheer curiosity. It describes his discovery of dephlogisticated
air and his lifelong belief in the phlogiston theory.
Antoine Lavoisier - the first
'modern' chemist tells part of Lavoisier's story, showing how his
work was based on meticulous experimentation and accurate quantitative
measurement. It describes the development of Lavoisier's new theory
of combustion, and the reasons for its relatively rapid acceptance by
the majority of scientists of the day in place of the phlogiston theory.
Activities
| Activity
1 |
|
- Students describe their own model of combustion by explaining
what happens when magnesium burns in air. They refer to the
phlogiston theory and comment on the differences between this
theory and the modern understanding of what happens when magnesium
reacts with air. Teachers can use this as an opportunity to
explore the extent to which students have the "correct"
model of combustion. Research cited in Driver
et al (1994:87-8) suggests that many 12 year-olds know that
oxygen is necessary for burning, although they do not appreciate
that it interacts with the burning material. The same source
suggests that perhaps as many as two-thirds of 15 year-olds
will fail to appreciate that mass is conserved in combustion.
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| Activity
2 |
|
- Students use the resources on Priestley and Lavoisier to comment
on the two very different styles of working which the two men
employed. They are asked to describe the men and their "personal
styles" in either text or drawing. Discussion can then
lead on to exploring whether either man's method of working
was "better" than the other's, and whether there is
a "proper" scientific method. Students and teachers
may like to consider how the model of investigations in Sc1
relates to the way in which Priestley and Lavoisier carried
out their science.
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| Activity
3 |
|
- Students write a letter EITHER from Priestley to Lavoisier
trying to convince him of the importance of phlogiston theory
OR from Lavoisier to Priestley trying to convince him of the
new theory of combustion. This is an opportunity for students
to consider the important role of communication and persuasion
in science - without the opportunity to communicate their ideas
in order to persuade others of them, where would the scientist
be?
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