Final answer:
Cocaine hydrochloride can be converted to its free base form, known as crack cocaine, by boiling it with a mixture that includes baking soda. The conversion is due to a chemical reaction that releases the free base form that is less soluble in water and vaporizes easily, making it suitable for smoking.
Step-by-step explanation:
Cocaine hydrochloride can be converted to its base form by boiling it with a mixture containing baking soda (bicarbonate of soda or sodium bicarbonate) until the water has evaporated. The solid residue that is collected after the evaporation process is commonly known as crack cocaine. Crack cocaine is more volatile than cocaine hydrochloride, meaning it can vaporize at lower temperatures, such as at the temperature of a burning cigarette. It's this property that allows crack cocaine to reach the brain very quickly when smoked, typically within 15 seconds.
When cocaine hydrochloride is mixed with baking powder (which contains sodium bicarbonate) and water, and then heated, the process helps to free the cocaine base from the hydrochloride salt. This occurs because baking soda, as a weak base, reacts with the hydrochloride, forming carbon dioxide and water in the process. The unneutralized base form of cocaine is less soluble in water and is more desirable for certain methods of consumption, like smoking, due to its ability to vaporize at lower temperatures compared to the salt form. This base form is what is referred to as crack cocaine, which are typically broken lumps of the processed cocaine.