Acids, Bases & pH

Acid

A substance that donates hydrogen ions (H+) to a solution, increasing the H+ concentration.

Base

A substance that accepts hydrogen ions (H+) and often releases hydroxide ions (OH-), decreasing the H+ concentration.

pH

A measure of the acidity or basicity of a solution, calculated as pH = -log[H+].

Buffer

A substance that minimizes changes to pH by absorbing or releasing hydrogen ions (H+) in a solution.

Hydronium ion

A water molecule that has gained a hydrogen ion (H+), represented as H3O+.

Hydroxide ion

An anion consisting of oxygen and hydrogen (OH-) that plays a key role in the pH of a solution.

Water ionization

The process by which water molecules spontaneously break into hydrogen ions (H+) and hydroxide ions (OH-).

Acidic solution

A solution where [H+] > [OH-], resulting in a pH less than 7.

Basic solution

A solution where [OH-] > [H+], resulting in a pH greater than 7.

Neutral solution

A solution where [H+] = [OH-], which occurs at a pH of 7.

Concentration of H+

The amount of hydrogen ions present in a solution, measured in molarity (M).

Ionization of water

The process that produces equal concentrations of H+ and OH- in pure water, typically 1 x 10^-7 M.

Logarithmic scale

A scale that represents values as powers of 10, used to calculate pH.

Lemon juice

An example of an acidic solution with a low pH.

Sodium hydroxide (NaOH)

A common base that releases hydroxide ions (OH-) into solutions and is classified as a strong base.

Sulfuric acid (H2SO4)

A strong acid that donates hydrogen ions (H+) in aqueous solutions.

Acidosis

A condition characterized by an excessively low pH in the blood.

Alkalosis

A condition characterized by an excessively high pH in the blood.

Carbonic acid (H2CO3)

An acid formed in the blood from dissolved carbon dioxide (CO2) that acts as a buffer.

Bicarbonate ion (HCO3-)

A conjugate base that helps to regulate blood pH by acting as a buffer.