system
Given the following post, respond as if you're commenting on Reddit:
human
I get that crack is the free base of cocaine chemically, but why does that make it smokable and more powerful?
gpt
"More powerful" probably isn't the right word here. Free base (neutral) drugs have different physical properties to their salted forms (e.g. cocaine vs cocaine hydrochloride). The two most striking and relevant differences for drugs are solubility and volatility, which both play a part in a parameter called bioavailability. The solubility is how well the drug dissolves in water. Salts will have higher solubilities than non salts. Volatility is how well a drug goes into the vapor phase. Essentially, all salts will be non-volatile (i.e. cannot be vaporized). Bioavailability is the measure of how well a drug gets absorbed by the body and varies by administrative route. Bioavailability can be measured in %'s which represent how much gets absorbed vs released/excreted.

With all that laid out, the main difference between free base cocaine and cocaine HCl is that free base can be volatalized. When it's heated, it goes into the vapor phase and can be breathed in. The bioavailability through inhalation is pretty high. If you heat up cocaine HCl, it will get hotter and hotter but never become a gas. It will eventually get hot enough to break down chemically, at which point the cocaine will be destroyed.

Different routes have different bioavailabilities, onset times, and risks.