Ch.4 - Reactions in Aqueous Solution

Brown - Chemistry: The Central Science 15th Edition

Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook

Brown 15th Edition

Ch.4 - Reactions in Aqueous Solution

Problem 78

Chapter 4, Problem 78

Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/mL at 15 °C. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL glycerol at 15 °C in enough water to make 250.00 mL of solution.

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

Verified step by step guidance

Calculate the mass of glycerol using its volume and density: \( \text{mass} = \text{density} \times \text{volume} \).

Convert the mass of glycerol to moles using its molar mass: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \). The molar mass of glycerol (C3H8O3) is calculated by adding the atomic masses of its constituent atoms.

Determine the volume of the solution in liters by converting 250.00 mL to liters: \( \text{volume in liters} = \frac{250.00 \text{ mL}}{1000} \).

Calculate the molarity of the glycerol solution using the formula: \( \text{Molarity} = \frac{\text{moles of solute}}{\text{liters of solution}} \).

Combine the results from the previous steps to express the molarity of the glycerol solution.

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). To calculate molarity, one must know the amount of solute in moles and the total volume of the solution in liters. This concept is essential for understanding how concentrated a solution is and is commonly used in chemistry for preparing solutions.

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 glycerol allows us to convert its volume into mass, which is necessary for calculating the number of moles of glycerol present in the solution. Understanding density is crucial for accurately determining the amount of solute in a given volume.

Molecular Weight

Molecular weight, or molar mass, is the mass of one mole of a substance, measured in grams per mole (g/mol). For glycerol (C3H8O3), the molecular weight can be calculated by summing the atomic weights of its constituent atoms: carbon, hydrogen, and oxygen. This value is vital for converting grams of glycerol into moles, which is a necessary step in calculating the molarity of the solution.

Recommended video:

Guided course

03:45

Weight Conversion Example

Related Practice

Textbook Question

(b) What volume of HCl is needed to neutralize 2.87 g of Mg(OH)₂?

1298

views

Textbook Question

Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL at 25 C. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid at 25 C in enough water to make 250.0 mL of solution.

(b) If you dilute 10.0 mL of the stock solution to a final volume of 0.250 L, what will be the concentration of the diluted solution?

1106

views

Textbook Question

(a) How many milliliters of a stock solution of 6.0 M HNO₃would you have to use to prepare 110 mL of 0.500 M HNO₃?

(d) If 45.3 mL of a 0.108 M HCl solution is needed to neutralize a solution of KOH, how many grams of KOH must be present in the solution?

628

views