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Chapter Analysis
Intermediate30 pages • EnglishQuick Summary
Chapter 1 of Chemistry Part 1 for Class 12 focuses on solutions, covering the types and formation of solutions primarily focusing on liquid solutions. Key concepts include expressing concentrations, Raoult's and Henry's laws, ideal and non-ideal solutions, and the colligative properties of solutions such as vapour pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. The chapter explains these properties in relation to the molar mass of the solute and gives insights into deviations from Raoult's law applied to binary liquid solutions.
Key Topics
- •Types of solutions
- •Concentration of solutions
- •Raoult's Law
- •Ideal and non-ideal solutions
- •Colligative properties
- •Osmosis and osmotic pressure
- •Henry's Law
- •Deviations from Raoult's Law
Learning Objectives
- ✓Describe the formation and classification of solutions
- ✓Express solution concentration in various units
- ✓Explain and apply Henry's Law and Raoult's Law
- ✓Differentiate between ideal and non-ideal solutions
- ✓Interpret deviations from Raoult's Law
- ✓Correlate colligative properties with molar mass
Questions in Chapter
Calculate the mass percentage of benzene (C6H6) and carbon tetrachloride (CCl4) if 22 g of benzene is dissolved in 122 g of carbon tetrachloride.
Answer: C6H6 = 15.28%, CCl4 = 84.72%
Page 6
The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if the Henry’s law constants for oxygen and nitrogen at 298 K are 3.30 × 107 mm and 6.51 × 107 mm respectively, calculate the composition of these gases in water.
Page 30
Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at 25°C, assuming that it is completely dissociated.
Page 30
Additional Practice Questions
Explain Raoult's Law and provide an example where it is applicable.
mediumAnswer: Raoult's Law states that the partial vapour pressure of each volatile component in a solution is directly proportional to its mole fraction in the solution. For example, in a binary solution of benzene and toluene, the partial pressure of benzene p_benzene = x_benzene * p_benzene^0, where x_benzene is the mole fraction of benzene and p_benzene^0 is the vapour pressure of pure benzene.
Describe the process and significance of osmosis in biological systems.
mediumAnswer: Osmosis is the movement of solvent molecules through a semipermeable membrane from a dilute solution into a more concentrated one. This process is essential in biological systems for maintaining cell turgor and the movement of nutrients and waste products. An example is the absorption of water by plant roots from the soil.
What is the difference between ideal and non-ideal solutions? Provide examples.
mediumAnswer: Ideal solutions obey Raoult's Law across all concentrations and have zero enthalpy and volume changes upon mixing, such as the solution of benzene and toluene. Non-ideal solutions do not obey Raoult's Law and may show deviations due to different interactions, such as acetone and chloroform, which show a positive deviation.
How can colligative properties be used to determine the molar mass of a solute?
hardAnswer: Colligative properties such as freezing point depression, boiling point elevation, and osmotic pressure depend on the number of solute particles. By measuring these properties and applying formulas like ΔT_f = i * K_f * molality, where i is the van't Hoff factor, one can calculate the molar mass of a solute.
Explain Henry's Law with a practical application.
easyAnswer: Henry's Law states that at constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. A practical application is in carbonated beverages, where CO2 is dissolved under high pressure and released as bubbles when the pressure is reduced by opening the bottle.