Textbook Question
13.122 When salt is spread on snow-covered roads at - 2 °C, the snow melts. When salt is spread on snow-covered roads at- 30 °C, nothing happens. Explain.
321
views
Ch.13 - Solutions & Their Properties
McMurry8th EditionChemistryISBN: 9781292336145
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement143
- Ch.2 - Atoms, Molecules & Ions134
- Ch.3 - Mass Relationships in Chemical Reactions149
- Ch.4 - Reactions in Aqueous Solution157
- Ch.5 - Periodicity & Electronic Structure of Atoms92
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory73
- Ch.7 - Covalent Bonding and Electron-Dot Structures47
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure51
- Ch.9 - Thermochemistry: Chemical Energy104
- Ch.10 - Gases: Their Properties & Behavior138
- Ch.11 - Liquids & Phase Changes43
- Ch.12 - Solids and Solid-State Materials56
- Ch.13 - Solutions & Their Properties98
- Ch.14 - Chemical Kinetics79
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Aqueous Equilibria: Acids & Bases94
- Ch.17 - Applications of Aqueous Equilibria125
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium66
- Ch.19 - Electrochemistry130
- Ch.20 - Nuclear Chemistry73
- Ch.21 - Transition Elements and Coordination Chemistry122
- Ch.22 - The Main Group Elements155
- Ch.23 - Organic and Biological Chemistry43
Chapter 13, Problem 118
What is the osmotic pressure in atmospheres you would expect for each of the following solutions? (a) 5.00 g of NaCl in 350.0 mL of aqueous solution at 50 °C (b) 6.33 g of sodium acetate, CH3CO2Na, in 55.0 mL of aqueous solution at 10 °C
Verified step by step guidance1
Step 1: Calculate the molarity of the solution. First, determine the number of moles of solute. For NaCl, use its molar mass to convert grams to moles. Similarly, do this for sodium acetate, CH3CO2Na.
Step 2: Convert the volume of the solution from milliliters to liters, as molarity is expressed in moles per liter.
Step 3: Use the formula for molarity (M = moles of solute / liters of solution) to find the molarity of each solution.
Step 4: Apply the formula for osmotic pressure: \( \Pi = iMRT \), where \( i \) is the van 't Hoff factor (2 for NaCl and 1 for sodium acetate), \( M \) is the molarity, \( R \) is the ideal gas constant (0.0821 L·atm/mol·K), and \( T \) is the temperature in Kelvin.
Step 5: Convert the given temperatures from Celsius to Kelvin by adding 273.15, then substitute all known values into the osmotic pressure formula to calculate the osmotic pressure for each solution.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Osmotic Pressure
Osmotic pressure is the pressure required to prevent the flow of solvent into a solution through a semipermeable membrane. It is directly proportional to the concentration of solute particles in the solution, as described by the formula π = iCRT, where π is osmotic pressure, i is the van 't Hoff factor (number of particles the solute dissociates into), C is the molarity of the solution, R is the ideal gas constant, and T is the temperature in Kelvin.
Recommended video:
Guided course
01:13
Osmotic Pressure Formula
Van 't Hoff Factor (i)
The van 't Hoff factor (i) indicates the number of particles into which a solute dissociates in solution. For example, NaCl dissociates into two ions (Na⁺ and Cl⁻), so its van 't Hoff factor is 2. Understanding this factor is crucial for calculating osmotic pressure, as it affects the effective concentration of solute particles in the solution.
Recommended video:
Guided course
02:50Van't Hoff Factor
Molarity and Temperature
Molarity (C) is defined as the number of moles of solute per liter of solution. It is essential to calculate the concentration of the solute in the given volume of solution. Additionally, temperature affects the osmotic pressure, as it is included in the formula (T in Kelvin). Therefore, converting Celsius to Kelvin and accurately determining molarity are key steps in solving osmotic pressure problems.
Recommended video:
Guided course
03:48Temperature vs Heat
Related Practice
Textbook Question
If cost per gram were not a concern, which of the following substances would be the most efficient per unit mass for melting snow from sidewalks and roads: glucose 1C6H12O62, LiCl, NaCl, or CaCl2? Explain.
673
views
Textbook Question
A solution prepared by dissolving 3.00 g of ascorbic acid (vitamin C, C6H8O6) in 50.0 g of acetic acid has a freez- ing point that is depressed by ΔT = 1.33 °C below that ofpure acetic acid. What is the value of the molal freezing- point-depression constant for acetic acid?
458
views
Textbook Question
A solution prepared by dissolving 5.00 g of aspirin, C9H8O4, in 215 g of chloroform has a normal boiling point that is elevated by ΔT = 0.47 °C over that of pure chloro- form. What is the value of the molal boiling-point-elevation constant for chloroform?
493
views
Textbook Question
Human blood gives rise to an osmotic pressure of approxi-mately 7.7 atm at body temperature, 37.0 °C. What must the molarity of an intravenous glucose solution be to give rise to the same osmotic pressure as blood?
966
views
Textbook Question
A solution of citric acid, C6H8O7, in 50.0 g of acetic acid has a boiling point elevation of ΔT = 1.76 °C. What is the molality of the solution if the molal boilin# g-point-elevation constant for acetic acid is Kb = 3.07 1°C kg2>mol.
797
views