# 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.

Mar 13, 2018

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 ($\text{H"^"+}$) from the acid and becomes a hydronium ion ($\text{H"_3"O"^"+}$).

The acid that has lost the $\text{H"^"+}$ (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

$\text{HC"_2"H"_3"O"_2"(aq)" + "H"_2"O(l)" ⇌ "C"_2"H"_3"O"_2^"-""(aq)" + "H"_3"O"^"+""(aq)}$

Carbonic acid

Carbonic acid ionizes in two steps.

$\text{H"_2"CO"_3"(aq)" + "H"_2"O(l)" ⇌ "HCO"_3^"-""(aq)" + "H"_3"O"^"+""(aq)}$

$\text{HCO"_3^"-""(aq)" + "H"_2"O(l)" ⇌ "CO"_3^"2-" "(aq)"+ "H"_3"O"^"+""(aq)}$