system
Given the following post, respond as if you're commenting on Reddit:
human
How can a candle make oxygen?

I was watching a show on submarines and they mentioned a chlorate candle that when burned release oxygen in emergency situations. My whole like i’ve known candles / fire to oxidize or use up oxygen. How can this candle generate oxygen?
gpt
Chlorate candles, or oxygen candles, consist of multiple substances.

One of which is sodium chlorate (NaClO3). If you heat sodium chlorate to a sufficiently high temperature, it falls apart into NaCl and O2, producing oxygen gas.

The other component of an oxygen candle is something that can produce the required heat for the reaction mentioned above to take place. This is typically iron powder. Oxidizing it generates plenty of heat and with the candle being wrapped in a thermal insulator, the amount of oxygen needed to maintain a sufficient heat level is considerably lower than the amount released by the sodium chlorate reaction.

So you're right that candles oxidize whatever it is they're burning. But in this case, the oxygen is not only an input into the reaction, but also a product of a different reaction taking place at the same time.