More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?

Question

Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of Hydrogen ions?

Answer 1

In general, the conductivity of any liquid increases with the concentrations of its ions, and decreases with their dimensions. In pure sulfuric acid, the only ions existing are $\ce{H3SO4+}$ and $\ce{HSO4-}$. They are big and their concentration is low. So the conductivity of pure sulfuric acid is low. But when you add some water, the $\ce{H2O}$ molecules are totally transformed into $\ce{H3O+}$ and $\ce{HSO4-}$ ions which are numerous and sometimes small (for $\ce{H3O+}$). The conductivity must increase.