Question

An arrow pointing downwards against one of the products in a chemical reaction indicates it is a/an ____________.

Answer 1

1. A downward arrow (⇣) indicates the formation of a precipitate.
2. A precipitate is the insoluble solid which settles down after the completion of the chemical reaction and comes out of the solution as a solid, frequently in the form of a suspension.

For example:

$$\begin{gathered} {\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{aq}\right)+{\mathrm{BaCl}}_2\left(\mathrm{aq}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{s}\right)\downarrow +2\mathrm{NaCl}\left(\mathrm{aq}\right) \\ (\mathrm{Sodium}\mathrm{carbonate})(\mathrm{Barium}\mathrm{choride})(\mathrm{White}\mathrm{precipitate}(\mathrm{Sodium}\mathrm{chloride}) \\ \mathrm{of}\mathrm{Barium}\mathrm{sulphate}) \end{gathered}$$

Therefore, an arrow pointing downwards against one of the products in a chemical reaction indicates it is a Precipitate.