Fire isn't necessarily hot, because it all depends on what's burning. typically, we burn wood and petrochemicals, like butane. Those fuel sources have relatively high ignition temperatures, so they burn hot. However, not all chemicals burn at the same temperature.
Here is a Wikipedia article on autoignition temperature, with a small table of chemicals and their burning temperatures.
This is a relevant AskScience thread on Reddit that expands more on the subject of flame temperature.
In short, fire is hot because fuels we burn have high ignition temperatures.
Well apparently For a short period of time, you can hold a burning cotton ball in your hand, provided it was lit with a relatively low ignition hydrocarbon (acetone or butane). video. You can't really sustainably hold your hand in the flame, though.
An experiment that you can do involves phosphorous, which spontaneously combusts at STP. Basically, when miniscule amounts are burning, not enough heat can be generated by the sustaining flame, making the flame not have a temperature increase far past the autoignition temperature. Source is on the second page. It also says in that article that not all phosphorous burns this coldly.
I should note that all burning raises the temperature from the fuel's point of combustion, oftentimes drastically. Quantity of fuel can also affect the temperature increase. as in the phosphorous experiment, it says a fairly sizable chunk of the same phosphorus can inflict serious burns. Hope this helps!
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Fire isn't necessarily hot, because it all depends on what's burning. typically, we burn wood and petrochemicals, like butane. Those fuel sources have relatively high ignition temperatures, so they burn hot. However, not all chemicals burn at the same temperature.
Here is a Wikipedia article on autoignition temperature, with a small table of chemicals and their burning temperatures.
This is a relevant AskScience thread on Reddit that expands more on the subject of flame temperature.
In short, fire is hot because fuels we burn have high ignition temperatures.
Which fuels would create fire cool enough for me to freely keep my hand in the flames?
Well apparently For a short period of time, you can hold a burning cotton ball in your hand, provided it was lit with a relatively low ignition hydrocarbon (acetone or butane). video. You can't really sustainably hold your hand in the flame, though.
An experiment that you can do involves phosphorous, which spontaneously combusts at STP. Basically, when miniscule amounts are burning, not enough heat can be generated by the sustaining flame, making the flame not have a temperature increase far past the autoignition temperature. Source is on the second page. It also says in that article that not all phosphorous burns this coldly.
I should note that all burning raises the temperature from the fuel's point of combustion, oftentimes drastically. Quantity of fuel can also affect the temperature increase. as in the phosphorous experiment, it says a fairly sizable chunk of the same phosphorus can inflict serious burns. Hope this helps!