Chapter 18, Problem 66A

Explain why equilibrium arrows are used in the ionization equations for some acids.

Interpretation Introduction

Interpretation:

The use of equilibrium arrows in ionization equations for some acids is to beexplained.

Concept introduction:

Equilibrium arrows are used in the equations in both reactants and products are present in the solution.

Answer to Problem 66A

Equilibrium arrows are used in ionization equations for weak acids because weak acids don’t ionize completely. There exists equilibrium between ionized products and unionized reactants.

Explanation of Solution

$HCOOH$ is weak acid, it remains in equilibrium with dissociated ions on dissolution as:

$HCOOH+H_{2}O\rightleftharpoons HCO{O}^{-}+H_3{O}^{+}$

That’s why Equilibrium arrow is used.

Conclusion

Thus, equilibrium arrows are used in ionization equations for weak acids.