What chemical is best for dissolving flesh? For a story?

HF won't do much to flesh, although it will go after the bony parts pretty well. Don't get any on you because it tends to migrate until it hits the bone and starts to eat it. supposedly very painfully.  Won't much affect the skin though. Phosphoric acid, on the other hand, won't react fast but it will eat your skin and flesh pretty good if you allow it to.  Burned a hole in my shoe once from an unseen drop of glacial H3PO4 (very strong phosphoric acid).  Didn't happen right away, only noticed it a few days later.

You would probably be best suited to use a powerful caustic oxidant (base oxidizer).  Finish up with an acid on the bony residues.

Inorganic solids tend to be salts made by combining a metal or alkali with a conjugate base of a weak acid, so tend to be amenable to destruction by strong acids. The conjugate base to a weak acid likes H+, which is, of course, why the acid is weak to begin with.  The base part won't let go of the H+ easily.  Flooding the place with lots of free H+ (via strong acid) will cause those bases to grab the H+ in place of whatever cation they have been attached to.

Organic compounds are not generally salts so not so amenable to acid attack as a general rule.  They are much more amenable to attack by oxidants or other powerful organic solvents.  Strong bases do affect organic acids, like fatty acids, though (which is the general idea of soap, really).  But lots of the body won't much react to the base, you need an oxidant.  Some nice sodium hypochlorite (bleach) with heat will do a lot of destruction, but perchloric acid or hot sodium perchlorate, well, that will work even better.  Just more hazardous (can make some pretty vigorous reaction, explosively so).

The best solution for destroying flesh would be a strong base (a caustic) with a powerful oxidant.  Use acid on the bony residues.

Here's an article for you:

https://www.chemistryworld.com/opinion/can-acid-di...

There was a case involving dissolving a murder victim in a vat of phosphoric acid. The court had chemists analyze the entire vat of acid and found "contaminates" consistent with a human body the size of the victim. I think the primary ion studied was calcium.

I don't have a source for that story. It might show up in a list of solved murders where a body was never found.

"really into criminal cases"

I think most people are, but won't admit it. My wife and I love Dateline and when an episode is over, we often promise to each other that we will not murder each other using a [insert weapon used].

I'm not sure hydrofluoric acid can do the job.  Besides, it's a gas, and dangerous to people besides the ones whose flesh is supposed to dissolve, and it's expensive, and hard to find for sale, and buying it might raise suspicion.

Sodium hydroxide is probably the best bet.  It's readily available, relatively cheap, and not difficult to use -- although it does need to be dissolved in a little water since it is a solid.

I have vaguely heard of disposing of bodies by putting them in quicklime (calcium oxide), but I am unsure of the details.  The Wikipedia entry about calcium oxide doesn't help much.

Strong bases are best to dissolve the body, examples would be sodium, potassium or calcium hydroxides. Heated to 300 degrees, a solution of a strong base can turn a body into tan liquid with the consistency of mineral oil in just three hours. This will just leave bones. A strong acid such as hydrochloric or sulfuric acid can then be used to dissolve the bone by leaching out the minerals.

Flesh?  Contrary to a popular TV show, HF is a weak acid and isn't going to do much other than soak through skin and dissolve bones... to some extent.

Alkaline hydrolysis is the way to go... keep in mind that does not however, dissolve the bones. Just the flesh.. which is what you asked about.

https://en.wikipedia.org/wiki/Alkaline_hydrolysis_...

there's actually a commercial process for cremating humans this way. 

https://www.cremationassociation.org/page/alkaline...  

***********

Roger the Mole

I'm surprised by your answer.  HF is a gas, that's true, but it's called "hydrogen fluoride" in gaseous state.  Once it's dissolved in water, we call it hydrofluoric acid.  Same as with HCl(g) (hydrogen chloride) and HCl(aq) (hydrochloric acid).  

I'm not sure why you didn't know that, it's pretty basic stuff, but... now you do.  cheers.