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Ch.13 - Solutions
Chapter 13, Problem 64d

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. d. mole fraction

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Key Concepts

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

Mole Fraction

Mole fraction is a way of expressing the concentration of a component in a mixture. It is defined as the ratio of the number of moles of a specific component to the total number of moles of all components in the solution. For a solution containing methanol and water, the mole fraction of methanol can be calculated by dividing the moles of methanol by the sum of the moles of methanol and water.
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Density and Volume Relationships

Density is defined as mass per unit volume and is crucial for converting between mass and volume when calculating concentrations. In this problem, the densities of methanol and water allow us to determine their masses from their respective volumes. Understanding how to manipulate these relationships is essential for calculating the total moles of each component in the solution.
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Concentration Units

Concentration can be expressed in various units, including molarity, mass percent, and mole fraction. Each unit provides different insights into the composition of a solution. In this case, calculating the mole fraction requires knowing the moles of each component, which can be derived from their masses and molar masses, emphasizing the importance of unit conversions in solution chemistry.
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Related Practice
Textbook Question

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. a. molarity

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Textbook Question

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. b. molality

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Textbook Question

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. c. percent by mass

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Textbook Question

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. e. mole percent

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Textbook Question

Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g/mL.)

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Textbook Question

One brand of laundry bleach is an aqueous solution containing 4.55% sodium hypochlorite (NaOCl) by mass. What is the molarity of this solution? (Assume a density of 1.02 g/mL.)

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