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molecular weight
noun
: the average mass of a molecule of a compound compared to ¹/₁₂ the mass of carbon 12 and calculated as the sum of the atomic weights of the constituent atoms
Examples of molecular weight in a Sentence
Recent Examples on the Web
What separates these drops from the crowd is the inclusion of niacinamide and dual molecular weight hyaluronic acid, which pull their weight to even the skin tone, smooth over fine lines, and give the skin a more youthful glow.
—Alyssa Brascia, Peoplemag, 30 Jan. 2024
Two molecular weights of hyaluronic acid lead the formula to replenish the skin's moisture levels and reveal a bouncier complexion.
—Lauren Valenti, Vogue, 12 Jan. 2024
Most new antibiotics are small molecules—those that have molecular weights of less than 600 daltons.
—Beth Mole, Ars Technica, 5 Jan. 2024
Cassini’s samples, analyzed by the spacecraft’s onboard mass spectrometer (an instrument that identifies compounds by their molecular weight), had initially revealed five types of molecules in the jets: water, carbon dioxide, methane, ammonia and molecular hydrogen.
—Ling Xin, Scientific American, 14 Dec. 2023
But hydrogen is a wily gas, with a molecular weight as light as molecules come.
—IEEE Spectrum, 31 July 2014
Hydrolyzed soy protein is made of low molecular weight peptides, which are highly digestible.
—Amber Smith, Discover Magazine, 23 Oct. 2022
It’s formulated with hydrolyzed proteins, which are composed of low molecular weight peptides that can be absorbed in the digestive tract to reduce risk of triggering an immune reaction.
—Amber Smith, Discover Magazine, 17 Oct. 2022
Delta 8 has a molecular weight of 314.47 g/mol and a boiling point of 175-178°C (347-352°F).
—Amber Smith, Discover Magazine, 3 Sep. 2023
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'molecular weight.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
First Known Use
1860, in the meaning defined above
Dictionary Entries Near molecular weight
Cite this Entry
“Molecular weight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/molecular%20weight. Accessed 10 Jun. 2024.
Kids Definition
molecular weight
noun
: the weight of a molecule equal to the sum of the weights of the atoms contained in it
Medical Definition
molecular weight
noun
: the mass of a molecule that may be calculated as the sum of the atomic weights of its constituent atoms
More from Merriam-Webster on molecular weight
Britannica.com: Encyclopedia article about molecular weight
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