Which of the following solutions is more concentrated? 1.75 M glucose or 1.75 m glucose in water?

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

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Understand the difference between molarity (M) and molality (m). Molarity is the number of moles of solute per liter of solution, while molality is the number of moles of solute per kilogram of solvent.

Recognize that both solutions have the same numerical value (1.75), but they are expressed in different concentration units (M and m).

Consider that molarity depends on the volume of the solution, which can change with temperature, while molality depends on the mass of the solvent, which is not affected by temperature.

To compare the concentrations, note that for dilute aqueous solutions, molarity and molality values are often similar, but they are not identical due to the density of the solution.

Conclude that without additional information about the density of the solution or the exact conditions, a direct comparison is not straightforward. However, generally, molarity is used for reactions in solution, while molality is used when temperature changes are involved.

주요 개념

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Molarity (M)

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is commonly used in chemistry to express the concentration of a solution, allowing for easy comparison between different solutions. In this case, 1.75 M glucose indicates that there are 1.75 moles of glucose dissolved in one liter of water.

Molality (m)

Molality is another measure of concentration, defined as the number of moles of solute per kilogram of solvent. Unlike molarity, which depends on the volume of the solution, molality is based on the mass of the solvent, making it useful for temperature-dependent scenarios. In this question, 1.75 m glucose means there are 1.75 moles of glucose per kilogram of water.

Comparison of Concentrations

To determine which solution is more concentrated, one must consider both molarity and molality. Molarity is affected by the total volume of the solution, while molality is based solely on the mass of the solvent. In this case, the comparison requires understanding how the solute's mass and the solvent's volume interact, as the density of water and the volume occupied by glucose can influence the overall concentration.