Why does adding water to boiling oil cause an explosion but nothing happens when adding oil to boiling water?
In: 200
Multiple things:
1g of water takes up about 1mL of volume (depends on temperature). 1 g of steam (at 1 atmosphere of pressure, also depends on temperature, but it doesn’t change the overall result.) takes up about 2700 mL. So if we add water to oil that is above the boiling point of water, then the water will boil into steam. Even worse, vegetable oil can be 100⁰F above the boiling point of water before it catches fire. That means the water can boil near instantaneously, expanding over 2700x its volume in a fraction of a second.
Also, water sinks in oil. Oil is less dense and floats on top. Meaning not only does the steam expand at a tremendous rate, it can push 300⁰F oil up and out along with it. If the oil is that hot, and it’s a gas stove, there’s a pretty good chance that it will combust. The rate of combustion is determined by the surface area of the oil. Since fire needs both fuel and oxygen (and heat, but we’ve got that covered already) the more fuel is in contact with the air, the faster it burns. So spraying tiny droplets of oil all over your kitchen, if it catches fire, it’s going to engulf in flames. If you drop about 1.5 tbsp of water, that expands to roughly a human-sized fireball in under a second. That’s a bad day.
Now let’s go the other way and put oil into boiling water. The water cannot be above 212⁰F because it wouldn’t be water anymore and we already know that oil can make it up to 100⁰ above that without issue, so no explosion. Hot things do expand a bit, but we’re talking a few percent, not a few thousand times. And some oil may have enough inertia to dip below the surface, but it will bob right back to the top so even if it did explode, it’s not going to push anything out with it.
Latest Answers