In chemistry, a free base is the neutral form of an amine or Lewis base, typically contrasted with salt forms like hydrochlorides, which are more water-soluble and stable. This distinction is crucial for recreational drugs, as cocaine hydrochloride (powder) decomposes when heated, whereas freebase cocaine (crack) melts at 98°C and can be vaporized and smoked. When smoked, blood buffered at pH 7.4 converts 94.19% of the cocaine into its acid form (calculated via the Henderson-Hasselbalch equation with a pKa of 8.61), leaving 5.81% to cross the blood-brain barrier, driven continuously by Le Chatelier's principle. Freebasing is typically prepared by extracting the hydrochloride with an alkaline solution and a non-polar solvent, or via trituration ("cooking") with baking soda to produce a solid rock. This chemical principle also explains traditional practices, such as chewing coca leaves with alkaline lime or betel nuts with limestone, which converts alkaloids like arecoline into their absorbable freebase form.