Question

What does the symbol of a double arrow indicate in a chemical reaction?

Answer 1

That the reaction has reached equilibrium..........

Explanation:

And if equilibrium applies to the following reaction:

`A+BrightleftharpoonsC+D`,

then by definition, `k_f[A][B]=k_r[C][D]`

And we can write, `k_r/k_f=K_"equilibrium"=([C][D])/([A][B])`, where `k_r/k_f=K_"equilibrium"` is the thermodynamic equilibrium constant. This must be measured, and has been measured meticulously for many chemical equilibria.