Playing with fire!

Part 1 - Phlogiston Theory

Johann Joachim Becher

True for the candle in the jar?

Getting the fire started – testing Phlogiston Theory

• Burning Magnesium and paper then weighing them

• Calculating mass of magnesium or paper in the evaporating basin

Safety

DO NOT LOOK DIRECTLY AT THE MAGNESIUM STRIP

WHEN BURNING!

Part 2 – Why was Phlogiston Theory incorrect?

1. What was the appearance of the magnesium before it was burned?

2. What was the appearance of the magnesium after it was burned?

3. Identify 2 things that were released from the magnesium and paper when placed in the flame.

4. If ‘Phlogiston’ (from phlogiston theory) was a substance that was thought to be released from matter when burning, would you have expected the weight of the magnesium strip and paper to have increased (weigh more) or decreased (weigh less)?

5. Do your results support the Phlogiston theory? If not, what do you think may have happened? (Clue: The magnesium has reacted with another element to form a compound)

Joseph Priestley Antoine-Laurent Lavoisier

Lavoisier's Theory• The brief history of Joseph Priestley (discoverer of oxygen) and

Antoine-Laurent Lavoisier (father of chemistry) and their contribution to science

• Priestley and Lavoisier both worked on experiments on gases• Priestley published his work on ‘dephlogisticated air’ (before

Scheele): found this dephlogisticated air’ contributed to making a flame more intense and shared his ideas with Lavoisier

• Lavoisier studied into the gas further and did more experiments, eventually leading him to believe that it was the ‘dephlogisticated air’ that combines with the flame during combustion, forming a new compound (therefore magnesium will be heavier)

• “What might this ‘dephlogisticated air’ be?”

Part 3 – Combustion Lesson Summary Worksheet

The Fire Triangle

Homework

• Priestly and Lavoisier Worksheet• Simulation: http

://www.wonderville.ca/asset/reaction-action (combustion reaction game)

• Chemical Reactions: Combustion Worksheet

Next lesson

Antoine Lavoisier and his theories on corrosion

What do you see?

• http://theshadowlands.net/spon.htm• http://mysteriesoftheunexplainedblog.blogspot.com.au/2011/07/s

pontaneous-human-combustion.html