What is the molality of each solution prepared in Problem 13.66?

Verified step by step guidance

Step 1: Understand the concept of molality. Molality (m) is defined as the number of moles of solute per kilogram of solvent. It is expressed as m = \frac{\text{moles of solute}}{\text{kilograms of solvent}}.

Step 2: Identify the solute and solvent in the solution from Problem 13.66. Determine the chemical formula and molar mass of the solute if not already given.

Step 3: Calculate the number of moles of solute. Use the formula: \text{moles of solute} = \frac{\text{mass of solute (g)}}{\text{molar mass of solute (g/mol)}}.

Step 4: Determine the mass of the solvent in kilograms. If the mass is given in grams, convert it to kilograms by dividing by 1000.

Step 5: Calculate the molality of the solution using the formula from Step 1. Substitute the values obtained in Steps 3 and 4 into the formula to find the molality.

Key Concepts

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

Molality

Molality is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per kilogram of solvent. It is expressed in units of moles per kilogram (mol/kg). Unlike molarity, which depends on the volume of the solution, molality is based on the mass of the solvent, making it particularly useful in situations where temperature changes may affect volume.

Moles of Solute

The number of moles of solute is a fundamental concept in chemistry that quantifies the amount of a substance. One mole is defined as 6.022 x 10²³ particles (Avogadro's number) of that substance. To calculate molality, one must first determine the moles of solute present in the solution, which can be derived from the mass of the solute and its molar mass.

Mass of Solvent

The mass of the solvent is crucial for calculating molality, as it serves as the denominator in the molality formula. It is important to measure the mass of the solvent in kilograms, as molality is defined per kilogram of solvent. This measurement is distinct from the total mass of the solution, which includes both solute and solvent, and is essential for accurate concentration calculations.

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