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
Ch.13 - Solutions
Chapter 13, Problem 66
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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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 expressed in moles per liter (mol/L) and is crucial for understanding how much solute is present in a given volume of solution. To calculate molarity, one must know the mass of the solute, its molar mass, and the total volume of the solution.
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Density
Density is the mass of a substance per unit volume, typically expressed in grams per milliliter (g/mL) or kilograms per cubic meter (kg/m³). In this context, the density of the bleach solution allows us to convert the mass of the solution into volume, which is necessary for calculating molarity. Knowing the density helps in determining how much solution corresponds to a given mass.
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Percent by Mass
Percent by mass 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. In this question, the 4.55% sodium hypochlorite indicates that there are 4.55 grams of NaOCl in every 100 grams of the solution. This information is essential for determining the amount of solute present for molarity calculations.
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Related Practice
Textbook Question
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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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An aqueous solution contains 36% HCl by mass. Calculate the molality and mole fraction of the solution.
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Open Question
An aqueous solution contains 5.0% NaCl by mass. How do you calculate the molality and mole fraction of the solution?
Open Question
Which beaker shows a greater decrease in liquid level after being left side by side on a lab bench for 1 week, a beaker with 100.0 mL of pure water or a beaker with 100.0 mL of seawater, and why?