Burning oxygen - how much is required to sustain a flame: results

The PicoLog graph below shows the measured results.


Fig2: Screen capture of PicoLog


  1. What two by-products were produced by the flame?
    The graph shows that heat and light are produced when the candle is burning. This can be seen on the graph by an increase in heat inside the jar during the experiment and an increase in light level after the candle was lit. Another by-product of burning oxygen is the production of CO2.
  2. At what point did the candle extinguish?
    When the candle is burning it produces light. The light level would have dropped to zero when the candle was extinguished. This is shown at about 25 seconds in our experiment.
  3. How does the graph show you that the candle uses oxygen?
    When the candle was sealed inside the container the % of oxygen inside the container started dropping.
  4. What oxygen level is required to keep the candle burning?
    The candle was extinguished after 30 seconds when the air was made up with 18.8% oxygen. This shows that the candle flame requires an oxygen level of greater than 18.8% oxygen to remain alight.


  • The candle extinguished in 30 seconds when the oxygen level was 18.8%.
  • The temperature in the glass rose by 2.6 °C.
  • During the experiment the oxygen level decreased to 17.8%.

Credits, comments and further info

This experiment was written by J Carey at Pico Technology.