Download Joseph Priestley`s Candle-Burning Experiment

Priestley lit a candle.
He then placed a
glass jar over it…
…and watched as
the flame gradually
died out.
Priestley lit a candle.
He then placed a
glass jar over it…
…and watched as
the flame gradually
died out.
Priestley reasoned that
something in the air
was necessary to keep
the flame burning.
Priestley then placed
fresh mint leaves
underneath the jar
and allowed the
entire setup to sit for
a few days.
A few days passed…
After a few days,
Priestley found that
he could relight the
candle and it would
burn for a while.
After a few days,
Priestley found that
he could relight the
candle and it would
burn for a while.
Priestley concluded that
the plant had produced
the substance required
for burning.
What substance was
consumed as the candle
burned the first time?
What must have been added to
the jar to enable the candle to
burn the second time?
Where did this oxygen
come from?
What do you think would happen if
Priestley had put the plant and candle
back in the jar for a few days then
once again tried to light the candle?
A. the plant would die
B. the plant would light on fire
C. the candle would light again
D. the candle would not light again
Suppose Priestley had put the plant
and jar into a dark closet for a few
days. Do you think the candle
would have lit again?
What does this tell you about
plants and oxygen?
A. plants do not need oxygen
B. plants produce oxygen all the time
C. plants produce as much oxygen as they need
D. plants produce oxygen in the presence of light
In another experiment,
Priestley put a mouse
under the jar and
waited to see what
would happen.
In another experiment,
Priestley put a mouse
under the jar and
waited to see what
would happen.
Sadly, the mouse
eventually died.
Later, Priestley put
a mouse under the
jar with fresh mint
leaves and waited to
see what would
happen.
To his surprise, both
the mouse and plant
survived for quite
some time.
What important substance
was produced by the plant?
What important substance
was produced by the mouse?
Why were both the plant
and the mouse able to
survive under the jar?
Figure 7-3
The products of
photosynthesis are
the chemical
ingredients for
cellular respiration,
while the products of
cellular respiration
are the chemical
ingredients for
photosynthesis.