- published: 30 Aug 2012
- views: 399563
Molar concentration, also called molarity, amount concentration or substance concentration, is a measure of the concentration of a solute in a solution, or of any chemical species, in terms of amount of substance in a given volume. A commonly used unit for molar concentration used in chemistry is mol/L. A solution of concentration 1 mol/L is also denoted as 1 molar (1 M).
Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. For use in broader applications, it is defined as amount of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase c:
Here, n is the amount of the solute in moles,N is the number of molecules present in the volume V (in litres), the ratio N/V is the number concentration C, and NA is the Avogadro constant, approximately 6.022×1023mol−1.
Or more simply: 1 molar = 1 M = 1 mole/litre.
In thermodynamics the use of molar concentration is often not convenient, because the volume of most solutions slightly depends on temperature due to thermal expansion. This problem is usually resolved by introducing temperature correction factors, or by using a temperature-independent measure of concentration such as molality.
In chemistry, the mass fraction is the ratio of one substance with mass to the mass of the total mixture , defined as
The sum of all the mass fractions is equal to 1:
Mass fraction can also be expressed, with a denominator of 100, as percentage by mass (frequently, though erroneously, called percentage by weight, abbreviated wt%). It is one way of expressing the composition of a mixture in a dimensionless size; mole fraction (percentage by moles, mol%) and volume fraction (percentage by volume, vol%) are others.
For elemental analysis, mass fraction (or "mass percent composition") can also refer to the ratio of the mass of one element to the total mass of a compound. It can be calculated for any compound using its empirical formula or its chemical formula
"Percent concentration" does not refer to this quantity. This improper name persists, especially in elementary textbooks. In biology, the unit "%" is sometimes (incorrectly) used to denote mass concentration, also called "mass/volume percentage." A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1 %" or "1 % m/v" (mass/volume). This is incorrect because the unit "%" can only be used for dimensionless quantities. Instead, the concentration should simply be given in units of g/mL. "Percent solution" or "percentage solution" are thus terms best reserved for "mass percent solutions" (m/m = m% = mass solute/mass total solution after mixing), or "volume percent solutions" (v/v = v% = volume solute per volume of total solution after mixing). The very ambiguous terms "percent solution" and "percentage solutions" with no other qualifiers continue to occasionally be encountered.
To see all my Chemistry videos, check out http://socratic.org/chemistry Confused about molarity? Don't be! Here, we'll do practice problems with molarity, calculating the moles and liters to find the molar concentration. We'll also have to use conversion factors to convert between grams and moles, and between milliliters and liters.
This tutorial is designed to illustrate the concept of molarity and includes several examples of how to calculate molarity and to use molarity values in calculations. https://www.thechemistrysolution.com
Learn how molarity and molality differ! Rishi is a pediatric infectious disease physician and works at Khan Academy. More free lessons at: http://www.khanacademy.org/video?v=4VltXjR64SU These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video.
A video made by a student, for a student. Showing how to find the molarity of a substance. Kansas University. Rock Chalk Jayhawk, KU!!!!!!!!! IGNORE: Stoichiometry. Biology. Chemistry. How to work practice problem. How to convert. moles to grams . grams to moles. how to. doing chemistry practice problems. science. how. to. do. science. intro college chemistry level. problems. molecular weight. neutrality. acid. base. calculations. molar. mole. molar unit. grams. weight. chemical. formula. empirical. molecular. science equations. easy problems worked. made easier. made easy. density. mass. volume. how to find them. finding density. finding volume. finding mass. how to find molarity. how to find molecular weight of anything! all chemistry equations keywords
To see all my Chemistry videos, check out http://socratic.org/chemistry Use molarity to convert between mass and volume in a solution. In this video, we'll look at how to use molarity as a conversion factor. If you know the molarity, you can solve for either the number of moles or the volume of a solution. Also, molarity is a ratio that describes the moles of solute per liter of solution.
To see all my Chemistry videos, check out http://socratic.org/chemistry What's the difference between molarity and molality? They are both measures of concentration, but molarity has to do with volume (in Liters) and molality has to do with mass (in kilograms). Also, molarity talks about the volume of the total solution (solute and solution combined), and molality is about mass of the solute and solvent separately.
Mr. Causey discusses solutions, dilutions and concentration. Mr. Causey shows you how to perform molarity calculations and how to use molarity to create specific dilutions. http://www.yourCHEMcoach.com SUBSCRIBE for more chemistry videos: http://bit.ly/1jeutVl Molarity - 2:38 Dilutions - 5:32 ABOUT MR. CAUSEY'S VIDEO ACADEMY Mr. Causey's Video Academy is an educational video series of short video lessons for chemistry, algebra and physics. You can get lessons on a variety of topics or homework helpers that show you how to solve certain problems. There are over 120 videos to choose from. CONTACT ME: mrcausey@mrcausey.com FOLLOW ME: http://www.twitter.com/#!/mrcausey http://www.twitter.com/#!/mr_causey http://pinterest.com/mistercausey/ http://www.facebook.com/profile.php?id=814523544...
This week, Hank elaborates on why Fugu can kill you by illustrating the ideas of solutions and discussing molarity, molality, and mass percent. Also, why polar solvents dissolve polar solutes, and nonpolar solvents dissolve nonpolar solutes. All that plus Henry's Law and why Coke = Burps. -- TABLE OF CONTENTS Molarity, Molality, and Mass Percent 1:34 Polar Solvents Dissolve Polar Solutes 2:21 Nonpolar Solvents Dissolve Nonpolar Solutes 2:21 Henry's Law 5:15 Coke=Burps 4:00 -- Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Tumblr - http://thecrashcourse.tumblr.com Support CrashCourse on Subbable: http://subbable.com/crashcourse
This general chemistry video tutorial focuses on Molality and how to interconvert into density, molarity and mass percent. This video has plenty of examples and practice problems for you to work on. 1. How To Calculate Molality Given The Grams of Solute and Solvent 2. Calculating Molarity From Mass and Volume in mL 3. How To Determine Molarity Using Density of Solution 4. Molarity to Molality Conversion 5. How To Find Molality Using Density and Molarity 6. How To Calculate Molality Using Mass Percent 7. How To Determine Molarity Using Mass Percent and Density 8. How To Convert Molality to Molarity Using The Density of The Solution 9. How To Calculate Mass Percent From Molality 10. Molarity and Molality to Mass Percent.
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