How much CO2 is produced in burning of a candle? I've been reading this book, page 149. In chapter 15 the following experiment is suggested,


  Fix a candle in a container. Fill the container with water. Light the candle and then cover it with an inverted glass.






It is said that the oxygen in the space of inverted glass will be used up and to fill the space that was previously occupied with oxygen the water level will rise.

My question is, when the wax burns since $\ce{CO2}$ is emitted, won't this $\ce{CO2}$ fill up the space of used up $\ce{O2}$? What amount of $\ce{O2}$ is used up and what amount of $\ce{CO2}$ is released in the burning of wax of candle?
Surely $\ce{CO2}$ will fill some of the space of used up $\ce{O2}$. Candles these days are commonly made out of paraffine, which is basically $\mathrm{C_{many}H_{many}}$. The equation may look as follows:
$$\ce{C31H64 + 47O2 -&gt; 31CO2 + 32H2O}$$
You see that we get approximately 2 moles of $\ce{CO2}$ for 3 moles of spent $\ce{O2}$, hence the decrease in volume.

Another factor is that $\ce{CO2}$ is much better soluble in water than other components of air, so over time (though not immediately) it will probably vanish from the glass and thus free some more space.

Yet another factor is that air in the glass is quite hot while the candle is burning. As soon as it cools down, it shrinks.