Chapter 1-4: Matter, Properties, and Energy

Objectives

• Classify examples of matter

• Distinguish between physical and chemical properties of matter

• Convert between units of energy

• Use specific heat to calculate heat

• Describe the changes of state between solids, liquids, and gases

Matters

Pure Substances and Mixtures

Matter is anything that occupies space and has mass. It exists in three states: solid, liquid, and gas.

• Pure Substances: Have a fixed composition. Examples: elements (e.g., aluminum), compounds (e.g., distilled water). Cannot be broken down into simpler substances by physical means.

• Mixtures: Combinations of two or more substances. Can be separated into pure substances. Two types:

  • Homogeneous Mixtures: Uniform composition throughout (e.g., air, salt water).

  • Heterogeneous Mixtures: Non-uniform composition (e.g., oil and water, salad).

Physical and Chemical Properties

Physical Properties

Characteristics that are directly observable and unique to a substance.

• Examples: Color, odor, volume, state, density, melting point, boiling point

Chemical Properties

Describe a substance's ability to form new substances. These properties determine how substances interact with other matter or energy.

• Examples: Reactivity with acid, flammability, rusting of iron

Physical and Chemical Changes

Physical Changes

Changes in one or more physical properties of a substance, but not its chemical composition.

• Examples: Boiling or freezing water, melting ice

Chemical Changes

Changes that result in the formation of new substances with different properties and compositions.

• Examples: Burning of wood, rusting of iron

Energy

Kinetic and Potential Energy

• Kinetic Energy: Energy of motion

• Potential Energy: Stored energy due to position or composition

Units of Energy

• Common units: calorie (cal), joule (J)

• 1 cal = 4.184 J

Specific Heat

Specific heat is the amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

• Formula: Where:

  • = heat (in calories or joules)

  • = mass (in grams)

  • = specific heat (in cal/g°C or J/g°C)

  • = change in temperature (°C)

Changes of State

Changes of state involve the conversion between solid, liquid, and gas phases. These changes require or release energy.

Heat of Fusion

The energy needed to convert 1 gram of solid to liquid at its melting point.

• For ethanol: 26.3 cal/g

• Example calculation:

• Formula:

Heat of Vaporization

The energy required to convert 1 gram of liquid to gas at its boiling point.

• For ethanol: 200 cal/g

• Formula:

Other Changes of State

• Sublimation: Solid to gas (e.g., dry ice)

• Deposition: Gas to solid

• Evaporation: Liquid to gas (below boiling point)

• Condensation: Gas to liquid

Summary Table: Changes of State and Associated Energy

Key Formulas

• Specific Heat:

• Heat of Fusion:

• Heat of Vaporization: