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Ch.14 - Solutions
Chapter 14, Problem 58a

An aqueous KNO3 solution is made using 55.3 g of KNO3 diluted to a total solution volume of 2.00 L. Calculate the molarity of the solution. (Assume a density of 1.05 g>mL for the solution.)

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1
Determine the molar mass of KNO_3 by adding the atomic masses of potassium (K), nitrogen (N), and oxygen (O).
Convert the mass of KNO_3 from grams to moles using the molar mass calculated in the previous step.
Calculate the volume of the solution in liters, which is already given as 2.00 L.
Use the formula for molarity: M = \frac{\text{moles of solute}}{\text{liters of solution}} to find the molarity of the KNO_3 solution.
Substitute the moles of KNO_3 and the volume of the solution into the molarity formula to find the molarity.

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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 units of moles per liter (mol/L). To calculate molarity, one must first determine the number of moles of the solute, which can be found by dividing the mass of the solute by its molar mass, and then divide that by the volume of the solution in liters.
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Moles and Molar Mass

A mole is a unit in chemistry that represents 6.022 x 10^23 entities (atoms, molecules, etc.). The molar mass of a substance is the mass of one mole of that substance, typically expressed in grams per mole (g/mol). To find the number of moles of a solute, the mass of the solute is divided by its molar mass, allowing for the conversion from grams to moles, which is essential for calculating molarity.
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Density and Volume Conversion

Density is defined as mass per unit volume and is typically expressed in grams per milliliter (g/mL) or grams per liter (g/L). In this problem, the density of the solution is given, which can be used to convert the total mass of the solution into volume if needed. Understanding how to manipulate density and volume is crucial for accurately calculating concentrations in solutions.
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