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Ch.9 Solutions
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 9, Problem 37

What is the difference between a 5.00% (m/m) glucose solution and a 5.00% (m/v) glucose solution?

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Understand the difference between (m/m) and (m/v) percentages: (m/m) stands for mass/mass, meaning the percentage is based on the mass of solute relative to the mass of the solution. (m/v) stands for mass/volume, meaning the percentage is based on the mass of solute relative to the volume of the solution.
For a 5.00% (m/m) glucose solution, this means 5.00 grams of glucose are dissolved in 100 grams of the solution. The total mass of the solution includes both the solute (glucose) and the solvent (e.g., water).
For a 5.00% (m/v) glucose solution, this means 5.00 grams of glucose are dissolved in 100 milliliters of the solution. The volume of the solution includes both the solute and the solvent.
Recognize that the key difference lies in the denominator: (m/m) uses mass of the solution, while (m/v) uses volume of the solution. This distinction can lead to different concentrations depending on the density of the solution.
To compare the two solutions, you would need to consider the density of the solution. If the density is provided, you can convert between mass and volume to determine how the two percentages relate quantitatively.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mass/Volume Percent (m/v)

Mass/Volume Percent (m/v) is a concentration unit that expresses the mass of solute in grams per 100 milliliters of solution. For example, a 5.00% (m/v) glucose solution contains 5 grams of glucose dissolved in enough water to make a total volume of 100 mL. This measurement is particularly useful in laboratory settings where precise liquid volumes are used.
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Mass/Mass Percent (m/m)

Mass/Mass Percent (m/m) is a concentration unit that indicates the mass of solute in grams per 100 grams of solution. A 5.00% (m/m) glucose solution means that there are 5 grams of glucose in a total mass of 100 grams of the solution. This measurement is often used when the density of the solution is relevant, as it provides a direct relationship between the mass of solute and the total mass of the mixture.
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Density and its Role in Solutions

Density is the mass per unit volume of a substance and plays a crucial role in understanding solutions. The difference in density between a solution and its components can affect how concentrations are expressed. For instance, a 5.00% (m/m) glucose solution may have a different density than a 5.00% (m/v) solution, leading to variations in the actual amount of glucose present when measured by volume versus mass.
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