Will Alcohol Left in a Car Spontaneously Combust?
3 Answers
Alcohol left inside a car can spontaneously combust. Taking commonly used 75% medical alcohol as an example, its ignition point is 20°C. During summer, midday outdoor temperatures can exceed 40°C, and when a vehicle is parked outside under direct sunlight, the interior temperature can rise above 50°C, significantly increasing the risk of alcohol combustion or explosion. Additional Information: 1. It is advisable to avoid storing alcohol in vehicles. If disinfection is necessary, find an open area to wipe the car interior with alcohol while ensuring proper ventilation afterward. 2. Besides disinfectant alcohol, perfumes containing alcohol can also combust when reaching certain temperatures. Therefore, flammable or explosive items should not be stored in cars.
It depends on the specific situation. I always keep medical alcohol in my car, but stored in a cool place in the trunk. The flash point of 75% medical alcohol is about 22°C, while the dashboard temperature can soar to 70°C in summer—if it coincidentally meets static sparks, it's risky. Last year in our neighborhood, a car's disinfectant alcohol bottle caught fire due to sunlight focusing, burning half of the seat. It's recommended to use dark glass bottles for alcohol, avoid placing it on the dashboard or seats where sunlight directly hits, and ideally use a fireproof sealed container. Also, items like perfumes, power banks, and lighters that can explode under high temperatures should never be left in the sun.
From a physics teacher's perspective: Alcohol self-ignition requires three conditions to be met simultaneously - vapor concentration, temperature, and ignition source. When a car is sealed in summer, the windshield creates a greenhouse effect, causing the dashboard temperature to be 20-30°C higher than ambient temperature. 500ml of 75% alcohol will continuously evaporate at 30°C environment. When the vapor concentration reaches the explosive limit range of 3.3%-19%, encountering sparks from the cigarette lighter or static electricity can cause flash ignition. A personal experience reminder: Once I left alcohol wipes on the driver's seat, and when opening the car door in the afternoon, I smelled strong alcohol fumes - it gave me quite a scare afterwards.
