Understanding the Relationship
* pH: A measure of the acidity or alkalinity of a solution. It's defined as the negative logarithm (base 10) of the hydrogen ion (H+) concentration.
* H3O+: The hydronium ion, which is essentially a hydrogen ion (H+) bonded to a water molecule (H2O). In aqueous solutions, H+ ions exist primarily as H3O+ ions.
The Equation
The relationship between pH and H3O+ concentration is:
pH = -log[H3O+]
Solving for [H3O+]
1. Rearrange the equation:
[H3O+] = 10^(-pH)
2. Plug in the pH value:
[H3O+] = 10^(-3.120)
3. Calculate:
[H3O+] ≈ 7.58 x 10^-4 M
Answer: The molar concentration of H3O+ in the cola is approximately 7.58 x 10^-4 M.
