Alkali vs. Alkaline — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Updated on October 13, 2023
Alkali refers to water-soluble bases that release hydroxide ions when dissolved. Alkaline describes the property of a substance having a pH greater than 7. Both relate to basicity but differ in context and usage.
Difference Between Alkali and Alkaline
Table of Contents
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Key Differences
Alkali is a specific term in chemistry that denotes bases which are water-soluble and that release hydroxide ions (OH-) when dissolved in water. These substances can neutralize acids and turn litmus paper blue. Alkaline, on the other hand, is an adjective describing the nature or property of a substance. When something is alkaline, it has a pH level greater than 7, indicating its basic quality.
An alkali is tangible, often referring to specific substances like sodium hydroxide (NaOH) or potassium hydroxide (KOH). These are actual compounds that can be handled, measured, and used in reactions. In contrast, alkaline is a descriptive term. When a solution is said to be alkaline, it means the solution has basic characteristics but doesn't necessarily specify which base is present.
It's crucial to understand that not all basic substances are alkalis. For a base to be an alkali, it must be water-soluble. So, while calcium carbonate is a base, it's not an alkali because it doesn't dissolve in water. Yet, if a solution contains dissolved calcium carbonate and has a pH greater than 7, it would be correct to describe that solution as alkaline.
In everyday language, alkali might be used to refer to specific basic substances, especially in industrial contexts. For instance, someone might speak of an "alkali metal" or an "alkali solution." Alkaline, on the other hand, might be used more broadly, such as in "alkaline batteries" or when discussing the "alkaline diet."
Comparison Chart
Definition
Water-soluble bases releasing hydroxide ions in solution.
Having a pH level greater than 7.
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Nature
Specific substances
Descriptive term
Examples
Sodium hydroxide, potassium hydroxide
Alkaline batteries, alkaline water
Usage in Chemistry
Refers to tangible basic compounds
Describes basic property of a solution or substance
Contextual Reference
Often used in industrial or specific chemical contexts.
Used more broadly, including in everyday contexts.
Compare with Definitions
Alkali
Substances that can neutralize acids producing salts.
Potassium hydroxide is an alkali that can neutralize hydrochloric acid.
Alkaline
Referring to the characteristic of being basic.
Alkaline batteries derive their name from the alkaline electrolyte they contain.
Alkali
Bases that are soluble in water.
Lithium hydroxide is an alkali due to its solubility in water.
Alkaline
Pertaining to substances with a pH greater than 7.
Soap water usually has an alkaline nature.
Alkali
Chemicals that can form alkaline solutions in water.
When added to water, caesium hydroxide behaves as a strong alkali.
Alkaline
Descriptive of basic properties in chemistry.
With a pH of 9, this solution is clearly alkaline.
Alkali
Specific compounds that turn litmus paper blue.
Sodium carbonate is an alkali that changes the color of red litmus to blue.
Alkaline
Opposite of acidic in terms of pH.
The blood in our veins is slightly alkaline.
Alkali
In chemistry, an alkali (; from Arabic: القلوي al-qaly "ashes of the saltwort") is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water.
Alkaline
Solutions or substances that can neutralize acids.
Baking soda has an alkaline effect when mixed with vinegar.
Alkali
A compound with particular chemical properties including turning litmus blue and neutralizing or effervescing with acids; typically, a caustic or corrosive substance of this kind such as lime or soda
Flint is not subject to chemical weathering except by strong alkalis
The reaction is followed by measuring the concentration of alkali at various times
Alkaline
Of, relating to, or containing an alkali.
Alkali
A carbonate or hydroxide of an alkali metal, the aqueous solution of which is bitter, slippery, caustic, and characteristically basic in reactions.
Alkaline
Having a pH greater than 7.
Alkali
Any of various soluble mineral salts found in natural water and arid soils.
Alkaline
Having a relatively low concentration of hydrogen ions.
Alkali
Alkali metal.
Alkaline
Of or relating to a common disposable battery made of zinc and manganese dioxide.
Alkali
A substance having highly basic properties; a strong base.
Alkaline
Of, or relating to an alkali, one of a class of caustic bases.
Alkali
(chemistry) One of a class of caustic bases, such as soda, soda ash, caustic soda, potash, ammonia, and lithia, whose distinguishing characteristics are dissolving in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue.
Alkaline
(chemistry) Having a pH greater than 7.
Alkali
(Western United States) Soluble mineral matter, other than common salt, contained in soils of natural waters.
Alkaline
An alkaline battery.
Alkali
Soda ash; caustic soda, caustic potash, etc.
Alkaline
Of or pertaining to an alkali or to alkalies; having the properties of an alkali.
Alkali
One of a class of caustic bases, such as soda, potash, ammonia, and lithia, whose distinguishing peculiarities are solubility in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue.
Alkaline
Relating to or containing an alkali; having a pH greater than 7;
Alkaline soils derived from chalk or limestone
Alkali
Soluble mineral matter, other than common salt, contained in soils of natural waters.
Alkali
Any of various water-soluble compounds capable of turning litmus blue and reacting with an acid to form a salt and water;
Bases include oxides and hydroxides of metals and ammonia
Alkali
A mixture of soluble salts found in arid soils and some bodies of water; detrimental to agriculture
Alkali
Water-soluble bases that release hydroxide ions in water.
When sodium hydroxide is dissolved, it acts as an alkali.
Common Curiosities
How does Alkaline differ from an Alkali?
Alkaline describes a substance's basic property (pH > 7), while alkali refers to specific water-soluble bases.
Can you give an example of an Alkali?
Sodium hydroxide (NaOH) is a common alkali.
What happens when an Alkali reacts with an acid?
An alkali reacts with an acid to produce salt and water.
Why are some batteries called Alkaline?
Alkaline batteries contain an alkaline (basic) electrolyte, usually potassium hydroxide.
Are all Alkalis also Alkaline?
Yes, because alkalis are bases and have a pH greater than 7, making them alkaline.
Can you name a common use of an Alkali in households?
Sodium bicarbonate, used in baking and cleaning, is a common household alkali.
What is an Alkali?
An alkali is a water-soluble base that releases hydroxide ions when dissolved in water.
Are all basic substances Alkalis?
No, only those bases that are water-soluble are alkalis.
Is distilled water Alkaline?
No, distilled water is neutral with a pH of 7.
What does it mean when a solution is Alkaline?
It means the solution has a pH greater than 7, indicating it's basic.
Can an Alkali be harmful?
Yes, strong alkalis like sodium hydroxide can be caustic and harmful to skin and eyes.
What's the importance of maintaining an Alkaline pH in the body?
An alkaline pH (slightly above 7) in the body can support optimal function and metabolic processes.
Is lemon juice Alkaline?
No, lemon juice is acidic, not alkaline.
What is the significance of Alkalis in industries?
Alkalis are used in various industries, including soap-making, paper production, and chemical manufacturing.
Why might someone follow an Alkaline diet?
Some believe an alkaline diet can improve health by reducing acidity in the body, though scientific evidence on its benefits is still debated.
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Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
