Skip to main content
Ch.13 - Solutions & Their Properties
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoMcMurry 8th EditionCh.13 - Solutions & Their PropertiesProblema 106
Capitolo 13, Problema 106

A 1.0 m solution of K2SO4 in water has a freezing point of -4.3 °C. What is the value of the van’t Hoff factor i for K2SO4?

Guida verificata passo dopo passo
1
Step 1: Understand the concept of the van’t Hoff factor (i), which represents the number of particles a compound dissociates into in solution. For K2SO4, it dissociates into 2 K+ ions and 1 SO4^2- ion, theoretically giving i = 3.
Step 2: Use the freezing point depression formula: \( \Delta T_f = i \cdot K_f \cdot m \), where \( \Delta T_f \) is the change in freezing point, \( K_f \) is the cryoscopic constant of water (1.86 °C kg/mol), and \( m \) is the molality of the solution.
Step 3: Calculate the change in freezing point \( \Delta T_f \) by subtracting the observed freezing point from the normal freezing point of water (0 °C).
Step 4: Rearrange the freezing point depression formula to solve for the van’t Hoff factor \( i \): \( i = \frac{\Delta T_f}{K_f \cdot m} \).
Step 5: Substitute the known values into the rearranged formula to calculate the van’t Hoff factor \( i \).

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Colligative Properties

Colligative properties are physical properties of solutions that depend on the number of solute particles in a given amount of solvent, rather than the identity of the solute. These properties include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. Understanding colligative properties is essential for determining how solute concentration affects the physical state of a solution.
Video consigliato:
Percorso guidato
01:26
Colligative Properties

Freezing Point Depression

Freezing point depression is a colligative property that describes the decrease in the freezing point of a solvent when a solute is added. The extent of freezing point depression is directly proportional to the molality of the solution and the van’t Hoff factor (i), which accounts for the number of particles the solute dissociates into. This concept is crucial for calculating the freezing point of solutions.
Video consigliato:
Percorso guidato
01:59
Freezing Point Depression

van’t Hoff Factor (i)

The van’t Hoff factor (i) is a dimensionless number that represents the number of particles into which a solute dissociates in solution. For ionic compounds like K2SO4, which dissociates into multiple ions (2 K+ and 1 SO4^2-), the van’t Hoff factor is greater than 1. Calculating i is vital for accurately applying colligative property equations, such as those used to determine freezing point depression.
Video consigliato:
Percorso guidato
02:50
Van't Hoff Factor
Pratica correlata
Domanda del libro di testo
What is the vapor pressure in mm Hg of the following solu-tions, each of which contains a nonvolatile solute? The vapor pressure of water at 45.0 °C is 71.93 mm Hg. (b) A solution of 10.0 g of LiCl in 150.0 g of water at 45.0 °C, assuming complete dissociation
1301
views
Domanda del libro di testo
Cyclopentane 1C5H102 and cyclohexane 1C6H122 are vola- tile, nonpolar hydrocarbons. At 30.0 °C, the vapor pres- sure of cyclopentane is 385 mm Hg, and the vapor pressure of cyclohexane is 122 mm Hg. What is Xpentane in a mixture of C5H10 and C6H12 that has a vapor pressure of 212 mm Hg at 30.0 °C?
333
views