Question

How to write an equation to show ionization?

Vinegar is a dilute solution of acetic acid (HC2H3O2). Carbonated water is a solution of carbonic acid (H2CO3). Write equations to show the ionization of each acid when placed into water. Note: both of these acids are weak acids. Weak acids ionize one hydrogen ion at a time if more than one hydrogen found in the chemical formula. Include the states of matter and balance the equations.

Answer 1

Here's how I would write the equations.

Explanation:

The acidic hydrogen atoms are at the beginning of the formulas. The other hydrogen atoms are not acidic.

The water removes an acidic hydrogen (`"H"^"+"`) from the acid and becomes a hydronium ion (`"H"_3"O"^"+"`).

The acid that has lost the `"H"^"+"` (the conjugate base) then gets a negative charge.

We write the equation as an equilibrium because both the forward and reverse processes are occurring at the same time.

Acetic acid

`"HC"_2"H"_3"O"_2"(aq)" + "H"_2"O(l)" ⇌ "C"_2"H"_3"O"_2^"-""(aq)" + "H"_3"O"^"+""(aq)"`

Carbonic acid

Carbonic acid ionizes in two steps.

`"H"_2"CO"_3"(aq)" + "H"_2"O(l)" ⇌ "HCO"_3^"-""(aq)" + "H"_3"O"^"+""(aq)"`

`"HCO"_3^"-""(aq)" + "H"_2"O(l)" ⇌ "CO"_3^"2-" "(aq)"+ "H"_3"O"^"+""(aq)"`