Why does oil/butter alone in a hot pan burn, but if you add food to the oil the oil doesn’t burn?

Question

Even if the pan appears to be at the same temperature

In: 1

Answer 1

The point of water (food typically has water in it) is to limit the temperature of whatever you’re cooking, to 100 Celsius 212 Fahrenheit. When a liquid starts to boil, the heat energy from the flame no longer raises the temperature of the liquid, but rather all of it goes into breaking away the liquid molecules so that they’re a (widely spaced) gas rather than a (closely spaced) liquid.

So oil and butter boil at a much higher temperature than the water in the food. And as soon as the food runs out of water (all of it boiled away), the temperature will start going up again and the food will be charred. The flames will start happening in the pan when the temperature of the oil is high enough to ignite.

And that’s why firefighters typically use water hoses at and around a fire: all of the heat from the fire goes into trying to boil all that water, and the wood materials get *a lot colder* and go under the “ignite” temperature.

Same thing happens with ice, by the way. No matter how hot it is outside, in a cup with ice water (or ice and soda), all of that heat energy goes into melting the water (ice) molecules from solid to liquid. So the entire cup stays at 0 Celsius 32 Fahrenheit until the ice has fully melted.