Nalorphine, a relative of morphine, is used to combat withdrawal symptoms in heroin users. How many milliliters of a 0.40% (m/v) solution of nalorphine must be injected to obtain a dose of 1.5 mg?
Ch.9 Solutions
Chapter 9, Problem 64
What is the concentration of a NaCl solution, in (m/v)%, prepared by diluting 65 mL of a saturated solution, which has a concentration of 37 (m/v)%, to 480 mL?
Verified step by step guidance1
Understand the problem: We are tasked with finding the new concentration of a NaCl solution in (m/v)% after diluting a given volume of a saturated solution to a larger volume. The key concept here is the dilution formula, which states that the amount of solute remains constant before and after dilution.
Write the dilution formula: \( C_1 V_1 = C_2 V_2 \), where \( C_1 \) is the initial concentration (37 (m/v)%), \( V_1 \) is the initial volume (65 mL), \( C_2 \) is the final concentration (what we are solving for), and \( V_2 \) is the final volume (480 mL).
Rearrange the formula to solve for \( C_2 \): \( C_2 = \frac{C_1 V_1}{V_2} \). This equation allows us to calculate the final concentration after dilution.
Substitute the known values into the formula: \( C_2 = \frac{(37 \text{ (m/v)%})(65 \text{ mL})}{480 \text{ mL}} \). Ensure that the units for volume are consistent (both in mL).
Simplify the expression to calculate \( C_2 \). The result will give the final concentration of the NaCl solution in (m/v)% after dilution.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Concentration (m/v)%
Concentration expressed as mass/volume percentage (m/v)% indicates the mass of solute in grams per 100 mL of solution. For example, a 37 (m/v)% NaCl solution contains 37 grams of NaCl in 100 mL of solution. This measurement is crucial for understanding how much solute is present in a given volume of solvent.
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Dilution
Dilution is the process of reducing the concentration of a solute in a solution, typically by adding more solvent. The dilution equation, C1V1 = C2V2, relates the initial concentration and volume (C1 and V1) to the final concentration and volume (C2 and V2). This concept is essential for calculating the new concentration after mixing solutions.
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Saturated Solution
A saturated solution is one in which the maximum amount of solute has been dissolved at a given temperature, resulting in an equilibrium between dissolved and undissolved solute. In this context, the initial saturated solution of NaCl at 37 (m/v)% serves as the starting point for dilution, influencing the final concentration of the diluted solution.
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