Chapter 18, Problem 5STP

Interpretation Introduction

Interpretation:

The strongest acid is to be found out in given table.

Concept introduction:

Acid ionization constant tells about equilibrium that whether reactants are favored or products.

For a reaction,

$HA+H_{2}O\rightleftharpoons A^{-}+H_3{O}^{+}$

Acid ionization constant is given by:

$\begin{array}{l}{k}_a=\frac{\left[A^{-}\right]\times \left[H_3{O}^{+}\right]}{\left[HA\right]}\\ where,\\ \left[A^{-}\right]isconcentrationof{A}^{-}\\ \left[H_3{O}^{+}\right]isconcentrationof{H}_3{O}^{+}\\ \left[HA\right]isconcentrationofHA\end{array}$

More the value of acid ionization constant, stronger is the acid.

Answer to Problem 5STP

C

Explanation of Solution

$pH$ of acid lies in range 1-7.

The acid which has minimum value of $pH$ is strongest.

Thus lutidinic acid with $pH=1.09$ is strongest acid among the four acids.

Conclusion

Due to minimum $pH$ of lutidinic acid option C is correct and other are incorrect.