[ moh-lar-i-tee ]
/ moʊˈlær ɪ ti /
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noun Chemistry.
the number of moles of solute per liter of solution.
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Origin of molarity

First recorded in 1930–35; molar3 + -ity
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What is molarity?

Molarity is the number of moles of solute per one liter of solution. The symbol for molarity is a capital M.

In chemistry, a solution is a mixture of two or more substances in which neither substance changes chemically. For example, salt water is a solution that contains water (the solvent) and salt (the solute). Concentration is the amount of dissolved substance in a solution. In other words, it is the amount of stuff that has been mixed into your liquid. Concentration is usually measured in molarity.

A mole is a basic unit in chemistry. It is the amount of a substance in grams that contains as many atoms, molecules, or ions as 12 grams of carbon-12 (6.022 x 1023) does. A mole of oxygen, for example, is 6.022 x 1023 atoms of oxygen.

Molarity is the number of moles of a solute per liter of solution. If we wanted to know the molarity of our saltwater solution, we’d want to know how many moles of salt are in every 1 liter of the water.

Why is molarity important?

The first records of the term molarity come from around 1930. It combines the word molar, an adjective that refers to moles, and the suffix ity, a suffix used to create abstract nouns that express a state.

Why do we care about molarity? Because it tells us how densely packed a substance is in a solution. Is there a lot of salt in the water or only a little bit? If you know the molarity of a solution, you can also determine the exact amount of substance (in grams) that is dissolved in a solution.

Did you know … ?

The actual metric unit of measurement of concentration is mole per cubic meter (mol/m3). Molarity is only concerned with a single liter, however, so we simplify the measurement by using mole per cubic decimeter (mol/dm3) instead. A cubic decimeter is equal to 1 liter.

What are real-life examples of molarity?

A student will usually discover whether they will enjoy chemistry during the same lesson that their teacher introduces molarity.

What other words are related to molarity?

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Molarity is the number of moles of solute per one liter of solution.

British Dictionary definitions for molarity

/ (mɒˈlærɪtɪ) /

another name (not in technical usage) for concentration (def. 4)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for molarity

[ mō-lărĭ-tē ]

The molar concentration of a solution, usually expressed as the number of moles of solute per liter of solution.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.