Ah, this is where it gets fun. Pure ethanol freezes at -173°F, but mix it with water, and the freezing point changes in a weird way. The mixture’s freezing point is actually lower than either liquid alone—a phenomenon called freezing point depression.
For example, a 50% ethanol/water mix freezes around -27°F (-33°C). That’s still super cold, but not as cold as pure ethanol. It’s like the two liquids share the stress of freezing, making each other more resilient.
This is why windshield washer fluid is often a mix of ethanol (or methanol) and water—it stays liquid in your car’s lines down to -20°F or lower. Pure water would just laugh and turn to ice, then your car would cry.
The “Moon” Test (Don’t Try This at Home)
Scientists have actually measured ethanol’s freezing point on the moon. Yes, the moon. At 2-3 Kelvin (that’s -456°F), ethanol does eventually freeze, but it forms a glassy solid instead of crystalline ice.
This is called amorphous solidification, and it’s rare for liquids. Ethanol basically says, “I’m too cool to make proper crystals. I’ll just go glassy instead.”
So if you ever visit a lunar base and want a cold drink, you’ll need some serious heating. But your ethanol? It’ll still be liquid until you hit the dark side of the moon. Science fiction, meet science fact.
