Overview
This lecture covers key skills in scientific notation, unit conversions using the factor label method, temperature scales and conversions, and definitions related to energy, heat, density, and specific gravity.
Scientific Notation and Calculators
- Scientific calculators allow easy entry of numbers in scientific notation using the EXP or EE button.
- Enter the decimal part first, then use the exponent key (EXP/EE) instead of "×10".
- Use the plus/minus (±) key for negative exponents.
Unit Conversions & The Factor Label Method
- The factor label method (dimensional analysis) converts units using conversion factors written as fractions.
- Always set up your data and multiply by conversion factors so units cancel appropriately.
- Conversion tables for English, metric, and English-metric conversions are provided during exams and for practice.
- Metric prefixes (e.g., milli-, kilo-, micro-) must be understood and are summarized in provided tables.
Worked Conversion Examples
- To convert 12 gallons to quarts: 12 gal × (4 qt / 1 gal) = 48 qt.
- To convert 10.0 cm to meters: 10.0 cm × (1 m / 100 cm) = 0.100 m (3 significant digits).
- Multi-step conversions link factors (e.g., ounces → pounds → kilograms).
- Always match significant figures in your answer to those given in the original data.
Temperature Scales and Conversions
- Three main temperature scales: Fahrenheit (°F), Celsius/Centigrade (°C), and Kelvin (K).
- Freezing and boiling points of water: 32°F/212°F, 0°C/100°C, and 273 K/373 K.
- Convert °C to °F: °F = (1.8 × °C) + 32; Convert °F to °C: °C = (°F − 32) / 1.8.
- Kelvin = °C + 273.15 (used later in the course).
Energy, Heat, and Temperature
- Energy is the ability to do work; kinetic energy is energy of motion, potential energy is stored energy.
- Heat is energy in transit, measured in calories or joules.
- Temperature measures the intensity of heat, not the amount (which also depends on mass).
Density and Specific Gravity
- Density = mass / volume (typically in g/mL or g/cm³).
- Mass, volume, or density can be found by rearranging the formula: mass = density × volume; volume = mass / density.
- Specific gravity = density of substance / density of water (unitless, requires same temperature for both).
Key Terms & Definitions
- Scientific notation — a way to express very large/small numbers using powers of ten.
- Factor label method — technique for converting between units using conversion factors.
- Conversion factor — ratio expressing how many of one unit equals another.
- Significant figures — digits that carry meaning in a measured quantity.
- Kinetic energy — energy of motion.
- Potential energy — stored energy.
- Density — mass per unit volume.
- Specific gravity — ratio of a substance’s density to that of water.
Action Items / Next Steps
- Print and review session notes, conversion worksheets, and extra notes from Blackboard.
- Practice additional conversion problems from worksheets and online resources.
- Review metric prefixes and conversion tables.
- Prepare for Session 2 and bring questions on any unclear material.