Question

What is a solid formed from liquid reactants during a chemical reactions.

Answer 1

That would be a Precipitate.
For example:

`BaCl_(2) _((aq)) + H_(2)SO_(4) _((aq)) -----\ \textgreater \ BaSO_(4)_((s)) + HCl_((aq))`

Barium Chloride is soluble thus a solution and so is Sulphuric Acid but when the Barium ions merge with the Sulphate ions this cause the product Barium Sulphate deposits from the mixture as a solid (precipitate)