Why does hand sanitizer heat up? While washing my hands with soap I added some hand sanitizer just because it was right there on the counter and couldn't resist mixing them... Ha!  However, when I added the hand sanitizer it heated up for a moment and then cooled back down.  Why does this happen?
Hand sanitizers are generally ~50% - 70% ethanol or isopropanol. When these alcohols mix with water, they may release heat. Starting at room temperature, mixing ~100% ethanol with an equal volume of water will raise the temperature of the mixture ~8 0C.