اے آئی مسودہ — ابھی کسی استاد نے جانچا نہیں۔ اپنے استاد سے تصدیق کریں۔

Chemistry · Class 9 · Chapter 6: Solutions

8 min

Key points

Solution is a homogeneous mixture of two or more substances — solvent is present in larger amount, solute in smaller amount
Solutions can be gaseous (air), liquid (sugar in water), or solid (alloys like brass)
Concentration can be expressed as percentage by mass, percentage by volume, or molarity
Solubility is the maximum amount of solute that can dissolve in 100g of solvent at a given temperature
Saturated solution contains maximum amount of solute at given temperature — no more solute can dissolve
Unsaturated solution can dissolve more solute, supersaturated contains more solute than normal solubility
Henry's Law states that solubility of gas in liquid is directly proportional to pressure of gas
Crystallization is the process of obtaining pure crystals from saturated solution by cooling or evaporation

Definitions

Solution: A solution is a homogeneous mixture of two or more substances in which the particle size is less than 1 nm
Solvent: The component of solution which is present in larger amount and dissolves the other component
Solute: The component of solution which is present in smaller amount and gets dissolved in solvent
Saturated Solution: A solution which contains maximum amount of solute that can be dissolved in given amount of solvent at a particular temperature
Solubility: The maximum amount of solute in grams that can dissolve in 100g of solvent at a given temperature to form saturated solution

Worked example

Define solution, solute and solvent. Calculate the molarity of a solution containing 20g of NaCl dissolved in 500ml of water. (6 marks)

Solution is a homogeneous mixture of two or more substances. Solute is the substance that is dissolved. Solvent is the substance that dissolves the solute. Molarity = 0.684 M

Common mistakes

Students confuse solute and solvent — remember solvent is in larger amount
Writing percentage by mass formula incorrectly — always write (mass of solute/mass of solution) × 100
Forgetting that solubility of gases decreases with temperature increase
Not mentioning temperature when defining saturated solution
Confusing saturated with concentrated solution — they are different concepts

Quick recap

Solutions are homogeneous mixtures where solute dissolves in solvent. Types include saturated, unsaturated, and supersaturated based on solubility limits. Concentration is measured by molarity (moles/L) and molality (moles/kg solvent). Solubility depends on temperature, pressure, and nature of substances.

Generated by AI from Sindh Textbook Board material; review state: ai_unreviewed. MCQs, past-paper references and examiner notes are held back until a teacher has checked them.