Overview
Covers metric system prefixes, unit conversions within the metric system, and conversions between metric and English units.
Metric System & Prefixes
- The metric system is based on powers of 10 and uses prefixes for multiples or fractions.
- Important prefixes: kilo (10³), centi (10⁻²), milli (10⁻³), micro (10⁻⁶), deci (10⁻¹).
- "μ" (Greek mu) or "mc" stands for micro.
- Main units: meter (distance), liter (volume), gram (mass), Celsius (temperature).
- Larger prefixes: giga (10⁹), tera (10¹²), as in gigabytes and terabytes.
Metric to Metric Conversions
- Convert by replacing the prefix with its power of ten (e.g., milli = 10⁻³).
- Example: 450 mg = 0.45 g (since 1 g = 1,000 mg).
Unit Relationships in Chemistry
- 1 cm³ = 1 mL = 1 × 10⁻³ L.
- Conversion factors can be written in different but equivalent forms.
Conversion Practice
- Start with the given value and unit.
- Cancel units step-by-step using conversion factors.
- Use powers of ten for metric conversions; use stated relationships for metric-English conversions.
English to Metric Conversions
- Example: 0.090 miles to inches.
- 1 mile = 1,760 yards; 1 yard = 36 inches.
- Multiply by conversion factors to cancel unwanted units.
Significant Figures
- Final answers must match the correct number of significant figures from the starting value.
- Round and use zeros as placeholders as needed.
Key Terms & Definitions
- Metric Prefix: Symbol added to a base unit for multiples or fractions.
- Significant Figures: Digits known with certainty plus one estimated digit.
- Conversion Factor: Ratio showing how many of one unit equals another.
Action Items / Next Steps
- Memorize metric prefixes and their meanings.
- Practice both metric and English conversions.
- Review and apply significant figures in calculations.