For a solution prepared by dissolving 28.4 g of glucose (C6H12O6) in 355 g of water with a final volume of 378 mL, calculate the concentration in each unit: a. molarity, b. molality, c. percent by mass, d. mole fraction, e. mole percent.

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Calculate the molar mass of glucose (C_6H_{12}O_6) by adding the atomic masses of all atoms in the formula.

Convert the mass of glucose (28.4 g) to moles using its molar mass.

For molarity (a), divide the moles of glucose by the volume of the solution in liters (convert 378 mL to liters).

For molality (b), divide the moles of glucose by the mass of the solvent (water) in kilograms (convert 355 g to kg).

For percent by mass (c), divide the mass of glucose by the total mass of the solution (glucose + water) and multiply by 100 to get the percentage.

Key Concepts

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

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is calculated using the formula M = moles of solute / volume of solution in liters. To find the moles of glucose, divide its mass by its molar mass (180.18 g/mol). This concept is essential for understanding how solute concentration affects chemical reactions and properties.

Molality

Molality is another concentration measure, defined as the number of moles of solute per kilogram of solvent. It is calculated using the formula m = moles of solute / mass of solvent in kg. Unlike molarity, molality is temperature-independent, making it useful in scenarios where temperature fluctuations may affect volume. This concept is crucial for calculations involving colligative properties.

Percent by Mass

Percent by mass (or mass percent) is a way to express the concentration of a component in a mixture, calculated as the mass of the solute divided by the total mass of the solution, multiplied by 100. This concept helps in understanding the composition of solutions and is particularly useful in fields like pharmaceuticals and food science, where precise concentrations are critical.

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