The density of toluene (C7H8) is 0.867 g/mL, and the density of thiophene (C4H4S) is 1.065 g/mL. A solution is made by dissolving 8.10 g of thiophene in 250.0 mL of toluene. (b) Calculate the molality of thiophene in the solution.
Ch.13 - Properties of Solutions
Chapter 13, Problem 52a
Calculate the number of moles of solute present in each of the following solutions: (a) 255 mL of 1.50 M HNO3(aq),
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Convert the volume from milliliters to liters by dividing by 1000.
Use the formula for molarity: \( M = \frac{n}{V} \), where \( M \) is the molarity, \( n \) is the number of moles, and \( V \) is the volume in liters.
Rearrange the formula to solve for the number of moles: \( n = M \times V \).
Substitute the given values into the equation: \( n = 1.50 \, \text{M} \times 0.255 \, \text{L} \).
Calculate the number of moles by performing the multiplication.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molarity (M)
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). Understanding molarity is essential for calculating the amount of solute in a given volume of solution, as it directly relates the volume of the solution to the number of moles present.
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Volume Conversion
In chemistry, it is often necessary to convert between different units of volume. In this case, milliliters (mL) must be converted to liters (L) since molarity is defined in terms of liters. The conversion factor is 1 L = 1000 mL, which is crucial for accurately calculating the number of moles of solute in a solution.
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Common Conversion Factors
Calculating Moles from Molarity
To find the number of moles of solute in a solution, the formula used is: moles = molarity × volume (in liters). This relationship allows for the direct calculation of moles when both the molarity and the volume of the solution are known, making it a fundamental concept in solution chemistry.
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Related Practice
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