Boric Acid Ion Release Explained
$H_3BO_3$, known as boric acid, has a specific behavior when dissolved in water.
Nature of Boric Acid: It acts as a weak Lewis acid. Instead of donating a proton ($H^+$) directly like Brønsted-Lowry acids, it accepts a hydroxide ion ($OH^-$) from water ($H_2O$).
Reaction Mechanism
The dissociation reaction in water is represented as:
$ H_3BO_3 + H_2O \rightleftharpoons [B(OH)_4]^- + H^+ $
This equation shows that one molecule of $H_3BO_3$ reacts with water to yield one borate ion ($[B(OH)_4]^-$) and one proton ($H^+$).
Proton Release Analysis
Boric acid is a very weak acid, indicated by its small acid dissociation constant ($K_a \approx 5.8 \times 10^{-10}$). Consequently, the extent of dissociation is low.
This means that, on average, only a fraction of the $H_3BO_3$ molecules in solution actually release an $H^+$ ion. The number of $H^+$ ions released per molecule is therefore less than one.
The description "The correct value lies between 1 and 1" signifies that while the reaction mechanism involves the potential release of one proton (characteristic of a monoprotic acid), the actual average number released per molecule is less than 1 due to weak dissociation.
Important Questions from Chemical Biology {p}K_a Henderson Hasselbalch
- The $pH$ of $10^{-8} \text{ M HCl (aq.)}$ is ________ (rounded off to two decimal places).
Given, $pK_w = 14$. The correct comparison of $pK_a$'s of $[Fe(H_2O)_6]^{2+}$, $[Fe(H_2O)_6]^{3+}$, $V_2O_5$ and $N_2O_5$ is
- Aspartate residues are found in the active sites of many enzymes. The pKa for the ${\beta}$-carboxylate of aspartate is 3.86. At physiological pH this group can function as
a) Assertion: Acidulates are added in soft drinks to provide a buffering action.
r) Reason: Buffers tend to prevent changes in pH and prevent excessive tartness.
Choose the correct answer from the following
- Acid rain with a pH of 4.0 is more acidic than the rain with a pH of 6.0 by
