Classification of Matter Lecture Notes

Introduction to Chemistry

• Chemistry: Study of composition, structure, properties, and changes of matter.
• Importance in engineering: Understanding materials, energy, and processes.

Classification of Matter

• Matter: Anything that occupies space and has mass.
• Divided into two main categories:
  • Pure Substances: Definite composition and distinct properties.
    • Compounds: Pure substances made from two or more elements combined chemically in fixed ratios.
  • Mixtures: Composed of two or more substances that can be separated by physical means.
    • Homogeneous Mixtures: Uniform composition throughout.
    • Heterogeneous Mixtures: Composition varies and can be separated physically.

Types of Mixtures

• Suspensions: Heterogeneous mixtures with solid particles that can settle.
• Colloids: Mixtures where particles do not settle and remain dispersed.

Properties of Matter

1. Physical Properties: Do not alter identity or composition (e.g., melting, freezing).
2. Chemical Properties: Changes that alter the substance (e.g., combustion, acidity).

Changes in Matter

• Physical Changes: Changes that do not alter the substance's composition (e.g., cutting, breaking).
• Chemical Changes: Substances transform into different substances (e.g., digestion, burning).

Units of Measurement

• Quantities: Length, weight, time, temperature, electric current, amount of substance, luminous intensity.
• Common Units:
  • Length: Meters
  • Mass: Kilograms
  • Time: Seconds
  • Temperature: Kelvin
  • Amount of Substance: Moles
  • Luminous Intensity: Candela

Scientific Notation

• Used to express large or small numbers:
  • Mega (10^6)
  • Kilo (10^3)
  • Centi (10^-2)
  • Milli (10^-3)
  • Micro (10^-6)

Significant Figures

• Digits that contribute to a number's precision.
• Rules:
  • Non-zero digits are always significant.
  • Leading zeros are not significant.
  • Captive zeros (between non-zero digits) are significant.
  • Trailing zeros are significant only if there is a decimal point.

Calculations Involving Significant Figures

• Addition/Subtraction: Result has the same number of decimal places as the measurement with the least decimal places.
• Multiplication/Division: Result has the same number of significant figures as the measurement with the least significant figures.

Temperature Conversions

• Relationships between Celsius, Fahrenheit, and Kelvin:
  • °C to °F: (°C × 9/5) + 32
  • °F to °C: (°F - 32) × 5/9

Density and Measurement Examples

• Density: Mass per unit volume (e.g., kg/m³).
• Measurement conversion factors used for various calculations.

Example Problems

• Example 1: Converting units and calculating volume, mass, etc.
• Example 2: Calculating amount of substance in solution based on density and concentration.
• Example 3: Finding volume of seawater needed to extract magnesium based on its concentration.
• Example 4: Concentration calculations for swimming pool chlorine solution.