Difference Wiki

pH vs. pOH: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on January 8, 2024
pH measures the concentration of hydrogen ions in a solution, indicating acidity or alkalinity, while pOH measures the concentration of hydroxide ions, inversely related to pH.

Key Differences

pH quantifies the acidity of a solution by measuring hydrogen ion concentration, while pOH focuses on the alkalinity through hydroxide ion concentration.
The pH scale ranges from 0 to 14, with lower values indicating higher acidity. Conversely, the pOH scale also ranges from 0 to 14, but lower values signify higher alkalinity.
pH and pOH are inversely related; their sum is always 14 in a neutral solution at 25°C. pH is calculated as -log[H+], and pOH as -log[OH-].
pH is widely used in chemistry, biology, and environmental science to assess the acidity of solutions, while pOH is less commonly used but important in understanding alkaline solutions.
Both pH and pOH are crucial in predicting the behavior of substances in chemical reactions, affecting solubility, reactivity, and biological compatibility.

Comparison Chart


Measures hydrogen ion concentration
Measures hydroxide ion concentration

Scale Range

0 (acidic) to 14 (alkaline)
0 (alkaline) to 14 (acidic)

Calculation Formula



Lower pH means more acidic
Lower pOH means more alkaline

Common Use

More common in general acidity analysis
Less common, focuses on alkalinity

pH and pOH Definitions


A measure of acidity in a solution.
The pH of lemon juice is around 2, making it very acidic.


A measure of alkalinity in a solution.
A solution with a pOH of 4 is quite alkaline.


PH indicates hydrogen ion concentration.
Pure water has a pH of 7, which is neutral.


POH indicates hydroxide ion concentration.
In pure water, the pOH is also 7, indicating neutrality.


PH is crucial in chemical reactions.
Adjusting the pH can change the rate of a chemical reaction.


POH is used in analyzing base solutions.
High pOH values are found in cleaning products.


PH affects biological processes.
Human blood maintains a pH around 7.4, slightly alkaline.


POH values also range from 0 to 14.
A pOH above 7 indicates an acidic environment.


PH values range from 0 to 14.
A pH lower than 7 indicates an acidic solution.


POH complements pH in understanding solutions.
Knowing both pH and pOH gives a complete acidity-alkalinity profile.


A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. The pH scale commonly in use ranges from 0 to 14.


(dated) Indicating that something is trivial and not worth consideration.


Abbr of phot


(dated) Expressing disagreement or irritation


Misspelling of pH


(dated) Expressing disgust or repulsion.


Initialism of physical health


(dated) Designating astonishment or that one is impressed.


A notation used in transcripts to indicate that the transcriber does not know the spelling, usually of a name, and has spelled it as it was pronounced (phonetically)


An exclamation expressing contempt or disgust; bah !


(chemistry) p(otential of) H(ydrogen); the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is acidic and less than 7 is basic)


What does pH stand for?

pH stands for "potential of hydrogen."

How is pH measured?

Using a pH meter or indicator paper, measuring hydrogen ion concentration.

Why is pH important in biology?

pH affects enzyme activity and cellular functions.

Can pH affect health?

Yes, incorrect pH levels in the body can lead to health issues.

What does pOH stand for?

pOH stands for "potential of hydroxide."

What is considered a neutral pH?

A pH of 7 is neutral, like pure water.

How do pH and pOH relate to water?

In pure water at 25°C, pH and pOH both equal 7.

What is the pOH of a neutral solution?

Like pH, a pOH of 7 is neutral at 25°C.

Is pOH important in environmental science?

Yes, especially in studying aquatic environments.

What is the pOH of a basic solution?

Less than 7.

Can pH be altered easily?

Yes, by adding acids or bases.

Is pOH commonly used in chemistry?

Less than pH, but it's important for understanding alkalinity.

How do pH and pOH sum up in a solution?

Their sum is always 14 at 25°C.

Does pOH play a role in industrial processes?

Yes, especially in chemical manufacturing.

How do pH and pOH affect aquatic life?

They determine the suitability of water for different species.

How is pOH calculated?

By taking the negative logarithm of the hydroxide ion concentration.

What is the pH of an acidic solution?

Less than 7.

Are there pH extremes in nature?

Yes, from highly acidic to highly alkaline environments.

Can pOH change in a solution?

Yes, by adding substances that affect hydroxide ion concentration.

Is pH important in food science?

Absolutely, for food preservation and safety.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

Trending Comparisons

Popular Comparisons

New Comparisons