Chemistry Fundamentals: Measurement and Calculation

Understanding Exact and Uncertain Values

• Exact Values

  • Obtained through counting or by definition.

  • Examples of defined exact conversions:

    • $1$ dozen $= 12$ items

    • $1$ day $= 24$ hours; $1$ hour $= 60$ minutes; $1$ minute $= 60$ seconds

    • $1$ yard $= 3$ feet; $1$ foot $= 12$ inches

    • $1$ gallon $= 4$ quarts; $1$ quart $= 4$ cups; $1$ cup $= 8$ fluid ounces

    • $1$ pound (avoirdupois) $= 16$ ounces; $1$ stone $= 14$ pounds