Question

what happens if bone is dipped in HCl

Answer 1

HCl is hydrochloric acid, strong acid. Bone is made of minerals, and the most prominent mineral is calcium. When a bone is dropped in HCl medium, the calcium of bone slowly starts dissolve due to the action of strong acid. HCl + Ca -> CaCl2 + H2.

Afterwards the bone is depleted of calcium but it does not "melt" because there are other minerals that make up the bone such as potassium, vitamins and collagen. Since calcium is the main mineral in the bone, the bone becomes brittle and more susceptible to breakage.

Answer 2

If a bone is placed in weak HCl, the mineral part is removed from it and the remaining organic framework is left behind. The bone is decalcified and it is soft, flexible and can be tied into a knot.