How much heat (not light) does a regular candle produce?

Answer

Best,

Answering this question correctly in every detail is a very difficult task, but I will try to give an approximate solution.

What do we all have at our disposal?

– 1l water (= 1kg water)

– tea lights

We assume that the temperature of the pot of water is room temperature (20^OC). In order for this water to boil, some amount of heat must be added. For water you need to add 4190J(Joule) of heat so that 1kg of water contains 1^OC will rise in temperature. The water should be 80^OC (= 100^OC-20^OC) rise in temperature, so a total of 335200J of heat is needed to bring the water to the boiling point.

We will get that heat from a candle. A candle consists of paraffin and when a candle burns, heat is released. If you burn 1kg of paraffin, 44MJ (=44000000J) of heat is released. From all this we can determine how much paraffin we need to boil this water. It turns out that only 7.62 g of paraffin is needed to produce sufficient heat. If you know that a tealight has 14g of paraffin, then you only need a little more than half of such a tealight to boil the water. Such a tea light usually takes 4 hours to burn up completely. It takes 2 hours and 10 minutes of patience to burn 7.62g candle.

So it doesn’t seem like a wise choice to cook your potatoes using tea lights anyway! Because after 2 hours and 10 minutes sufficient heat has been released. In practice, however, it will be a lot more difficult to get the water to boil. In the previous reasoning I have assumed that all the heat emanating from the candle remains in the heated water. Naturally, during the heating of the water by the candle, the water itself will give off heat to the cold room. Because of that loss of heat, it will take much longer to boil the water. It is even quite possible that 1 tea light is not enough to make the water boil and that the heat given by 1 tea light is only enough to heat the water to a certain temperature lower than the boiling temperature.

If you ever try this out in real life, please let me know what your findings are 🙂

Kind regards.