Chemistry Chapter 1 Quiz

Overview of Chemistry

• Chemistry is defined as the study of matter, its properties, the changes it undergoes, and the energy associated with those changes.
• Matter is anything with mass and volume, including everyday objects like books and trees.

Key Definitions

• Composition: Refers to the types and amounts of substances that make up a sample of matter.
• Properties: Attributes that give each substance a unique identity, categorized into physical and chemical properties.

Physical States and Properties

• Physical Properties: Characteristics observed without interaction with other substances (e.g., color, melting point, boiling point).
• Chemical Properties: Properties that emerge when a substance interacts or transforms into other substances (e.g., flammability, corrosiveness).

Changes in Matter

• A change of state is a physical change where the form alters but composition remains unchanged; it is reversible via temperature changes.
• Chemical changes alter substance composition and cannot simply revert through temperature adjustments.

Scientific Measurement and Units

• SI Base Units include:
  • Mass: kilogram (kg)
  • Length: meter (m)
  • Time: second (s)
  • Temperature: kelvin (K)
  • Electric current: ampere (A)
  • Amount of substance: mole (mol)
  • Luminous intensity: candela (cd)

Conversion Factors and Calculations

• Conversion Factor: A ratio of equivalent quantities used to convert between different units.
• Example: 1 mile = 5280 feet leads to the conversion factor of 1 mi / 5280 ft.

Density

• Density Formula: Density is calculated as mass divided by volume.
• Density is a characteristic physical property at specific temperature and pressure conditions.

Common Densities

• Selected substance densities at room temperature (20°C):
  • Hydrogen: 0.0000899 g/cm³ (gas)
  • Water: 0.998 g/cm³ (liquid)
  • Gold: 19.3 g/cm³ (solid)

Significant Figures

• All measurements include uncertainty; the last digit is always estimated.
• The number of significant figures reflects the certainty of a measurement.

Precision, Accuracy, and Error

• Precision: Closeness of measurements to each other.
• Accuracy: Closeness of a measurement to the actual value.
• Systematic Error: Consistent bias in measurements (higher/lower than actual).
• Random Error: Fluctuates both above and below the true value.

Extensive vs. Intensive Properties

• Extensive Properties: Dependent on the quantity of the substance (e.g., mass, volume).
• Intensive Properties: Independent of the quantity of substance (e.g., density).