Introduction to Chemistry Quiz

Introduction to Chemistry

• Chemistry is the study of how matter changes and its associated energy.
• Matter is anything that has mass and volume.

Classifying Matter

• There are two ways to classify matter: by its physical state and by its chemical constitution.

States of Matter

• Solid: Rigid, incompressible, fixed shape and volume
• Liquid: Relatively incompressible, fluid, fixed volume but no fixed shape
• Gas: Easily compressible, fluid, adapts to container shape and volume

Chemical Constitution of Matter

• Element: Cannot be broken down into simpler substances by chemical reactions. Examples: Na, H, O
• Compound: Composed of two or more elements chemically bonded. Examples: H2O, H2, O2, NaCl
  • Compounds have properties different from their constituent elements.
  • Compounds have constant proportions of elements by mass, known as the Law of Constant Composition.
• Mixture: Can be separated into two or more substances by physical methods.
  • Mixtures have variable composition and do not follow the Law of Constant Composition.
  • Heterogeneous mixture: Has physically distinct parts with different properties. Example: A mixture of iron filings and copper
  • Homogeneous mixture (solution): Uniform throughout with consistent properties. Example: Salt dissolved in water

Chemical Change vs. Physical Change

• Chemical change: Forms a new substance with a different composition. Example: Water decomposing into hydrogen and oxygen gas.
• Physical change: Alters the form of a substance without changing its composition. Example: Water changing from solid (ice) to liquid.

Law of Conservation of Mass

• The total mass remains constant during a chemical change (reaction). In other words, mass is neither created nor destroyed.

SI Base Units and SI Prefixes

• The International System of Units (SI) is used for scientific measurement.
• It has seven base units from which all other units can be derived.

Temperature Units

• Celsius (°C):
  • 100 °C boiling point of water
  • 0 °C melting point of ice
• Fahrenheit (°F):
  • 212 °F boiling point of water
  • 32 °F melting point of ice
• Kelvin (K):
  • 373.15 K boiling point of water
  • 273.15 K melting point of ice
• Conversion formulas:
  • °F = (°C x 1.8) + 32
  • °C = (5/9) (°F - 32)
  • K = °C + 273.15
  • °C = K - 273.15