pH Master Glossary
A reference for academic and laboratory chemistry terminology.
Hover over underlined terms throughout the site to see quick definitions.
pH
A numeric scale used to specify the acidity or basicity of an aqueous solution.
It is the fundamental measurement for chemistry, biological health, and industrial processes.
Acidic
A solution with a pH less than 7.0, characterized by a high concentration of hydrogen ions.
Acids play key roles in everything from digestion to battery technology.
Alkaline
A solution with a pH greater than 7.0, also referred to as basic.
Alkaline solutions like soaps are essential for cleaning and neutralizing acids.
Neutral
A solution with a pH of exactly 7.0 (at 25°C), such as pure water.
It represents the balance point between acidic and basic properties.
Logarithmic Scale
A nonlinear scale where each unit change represents a 10-fold increase or decrease in concentration.
It allows us to represent huge variations in ion concentration with small, manageable numbers (0-14).
Hydrogen Ion (H+)
A single proton with a positive charge, released by acids in solution.
The concentration of these ions is what the pH scale actually measures.
Hydroxide Ion (OH-)
A diatomic anion consisting of an oxygen and hydrogen atom.
Bases increase the concentration of these ions to counteract acidity.
Buffer
A solution that resists changes in pH when small amounts of an acid or base are added.
Essential for maintaining stable pH in human blood and natural ecosystems.
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Alkalinity
The capacity of water to resist acidification (neutralize acids).
High alkalinity 'buffers' water, preventing rapid pH swings that can harm life.
Calibration
The process of adjusting a measuring instrument (like a pH meter) using a known standard (buffer).
Ensures that readings are accurate and repeatable over time.
Dilution
The process of decreasing the concentration of a solute in a solution, usually by adding more solvent (water).
Adding water to an acid will raise its pH toward neutral by lowering H+ concentration.
Litmus Paper
A piece of paper treated with natural water-soluble dyes that acts as a pH indicator.
Provides a quick, visual 'yes/no' check for acidity or alkalinity.
Indicator
A chemical substance that changes color depending on the pH of the solution it is in.
Crucial for visual titration and simple home test kits.
Probe / Electrode
The sensor part of a digital pH meter that detects the electrical potential of a solution.
Requires careful maintenance to remain accurate.
Molarity
A unit of concentration measuring the number of moles of solute per liter of solution.
Used to quantify exact chemical concentrations in lab settings.
Concentration
The amount of a substance (solute) present in a given volume of solution.
Directly determines the pH level of any given acid or base.
Aqueous Solution
Any solution in which water is the solvent.
The pH scale is specifically designed to describe chemistry happening in water.
Dissolution
The process by which a solute dissolves in a solvent to form a solution.
Acidic or basic properties only activate once a substance has dissolved.
Solubility
The maximum amount of a substance that will dissolve in a given amount of solvent at a specific temperature.
Limits how strong an acid or base can be made.
Neutralization
A chemical reaction in which an acid and a base respond with each other to form water and a salt.
The primary method for cleaning up dangerous chemical spills.
Titration
A technique where a solution of known concentration is used to determine an unknown concentration.
Standard laboratory procedure for verifying acid/base strength.
Salt
An ionic compound produced by the neutralization reaction of an acid and a base.
Not just 'table salt', but a whole class of chemical compounds.
pOH
The measure of hydroxide ion (OH-) concentration in a solution.
Mathematically, pH + pOH = 14 always at 25°C.
Strong Acid
An acid that completely dissociates into its ions in an aqueous solution.
Results in a very low pH even at low concentrations.
Weak Acid
An acid that only partially dissociates into its ions (e.g., citric acid).
Common in food and beverages; less corrosive than strong acids.
Strong Base
A base that fully dissociates in water (e.g., sodium hydroxide).
Results in a very high pH level, often near 14.
Weak Base
A base that does not fully dissociate in water (e.g., ammonia).
Useful for cleaning products where extreme caustic properties are not desired.
Standard Solution
A solution containing a precisely known concentration of a substance.
Used as a reference point for all other chemical measurements.
Reagent
A substance added to a system to cause a chemical reaction or see if one occurs.
Essential components of testing kits.
Molar Mass
The mass of one mole of a substance (g/mol).
Needed to calculate how much chemical to add to a solution.