Solutions (VSAQs)

Chemistry-2 | 2. Solutions – VSAQs:
Welcome to VSAQs in Chapter 2: Solutions. This page features the key FAQs for Very Short Answer Questions. Each answer is provided in simple English and follows the exam format. This approach helps you focus on essential points and secure top marks in your final exams.

VSAQ-1 : State Raoult’s law.

Understanding Raoult’s Law Simply:

  1. What: Raoult’s Law explains solution behavior, particularly vapor pressure.
  2. When: Applicable to dilute solutions with non-evaporating solutes.
  3. Main Idea: The addition of a non-evaporating solute to a liquid decreases its evaporation rate, influenced by the solute amount.
  4. Key Term: Mole fraction (X) – indicates the solute’s quantity in the solution.

VSAQ-2 : State Henry’s law.

Understanding Henry’s Law Simply:

  1. What: Henry’s Law describes the relationship between gas solubility and pressure.
  2. When: Applicable to gases dissolved in liquids.
  3. Main Idea: The solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid.
  4. Key Term: Solubility – the amount of gas that can dissolve in a liquid at a specific temperature and pressure.

VSAQ-3 : Define Osmotic Pressure.

Osmotic pressure is the pressure exerted by a solvent through a semipermeable membrane to equalize its concentration on both sides. This occurs when two solutions of different concentrations are separated by a semipermeable barrier that allows solvent molecules to pass but blocks solute molecules. Osmotic pressure plays a crucial role in biological systems, chemistry, and industrial processes involving solutions and membranes, where it helps in understanding processes like water movement in cells and the behavior of solutions with varying solute concentrations.

VSAQ-4 : What are isotonic solutions?

Isotonic solutions are solutions that have the same osmotic pressure as a reference solution. In the context of biological systems, like blood cells, isotonic solutions have the same concentration of solute particles as the fluid inside the cells. This ensures that there is no net movement of water across the cell membrane, maintaining the cell’s shape and preventing it from either swelling or shrinking. Isotonic solutions are commonly used in medical settings, such as intravenous (IV) fluids, to replace lost fluids in a way that doesn’t disrupt the normal functioning of cells.

VSAQ-5 : What is relative lowering of vapour pressure?

Relative lowering of vapor pressure is a term used in the context of Raoult’s law and describes the reduction in the vapor pressure of a solvent in a solution compared to the vapor pressure of the pure solvent. The relative lowering of vapor pressure (ΔP0/ΔP) is calculated by taking the difference between the vapor pressure of the pure solvent (P0) and the vapor pressure of the solution (P) and then dividing it by the vapor pressure of the pure solvent. It is a measure of the decrease in vapor pressure caused by the presence of a non-volatile solute in the solution and is directly proportional to the mole fraction of the solute in the solution.

VSAQ-6 : What are colligative properties? Give any one.

Colligative properties are physical properties of solutions that depend on the concentration of solute particles but not on their chemical identity. One colligative property is osmotic pressure, which is the pressure required to prevent the flow of solvent molecules into a solution through a semipermeable membrane. Osmotic pressure depends on the concentration of solute particles in the solution and is used in various applications, such as in medicine for determining the concentration of proteins or particles in blood.

VSAQ-7 : Define Elevation of boiling point.

Elevation of boiling point is a colligative property of solutions. It refers to the increase in the boiling point of a solvent when a non-volatile solute is added to it. This increase in boiling point occurs because the presence of the solute lowers the vapor pressure of the solvent, making it necessary for the solvent to reach a higher temperature to boil and overcome the reduced vapor pressure. Elevation of boiling point is directly proportional to the concentration of the solute particles in the solution and is one of the key principles explained by Raoult’s law. It has practical applications in various fields, including chemistry and industry, where it is used for purposes such as antifreeze formulations in automobiles.

VSAQ-8 : What is Ebullioscopic constant?

The ebullioscopic constant, denoted as Ke​, is a fundamental constant associated with a specific solvent and is used in the context of colligative properties. It quantifies the extent to which the boiling point of a solvent is elevated when a non-volatile solute is added to it. Mathematically, it is expressed as ∆Tb​ = Ke​× m, where ∆Tb​ represents the elevation in boiling point, m is the molality of the solution (the amount of solute in moles per kilogram of solvent), and Ke​ is the ebullioscopic constant. Different solvents have different ebullioscopic constants, making it a useful parameter for predicting and understanding changes in the boiling points of solutions due to the presence of solutes.

VSAQ-9 : What is Cryoscopic constant?

Cryoscopic Constant

  1. Definition: The Cryoscopic constant (𝐾𝑓) indicates how much the freezing point drops when a certain amount of solute is added.
  2. Specifics: When one mole of a non-volatile solute is mixed with 1 kg of solvent, the decrease in freezing point is given by the value of 𝐾𝑓.
  3. Importance: It helps in understanding the effect of solutes on freezing points.