chem q 1
- Science: Systematic study of the natural world through
observation and experimentation.
- Chemistry: Study of matter, its properties, and changes.
- Technology: Application of scientific knowledge for
practical purposes.
2.2 Importance of Green and Sustainable Chemistry
- Green Chemistry: Reduces or eliminates hazardous
substances.
- Sustainable Chemistry: Meets present needs without
harming future generations.
- Importance: Protects environment, reduces waste,
conserves resources.
2.3 Hypothesis, Scientific Law, Theory, Model
- Hypothesis: Testable explanation or prediction.
- Scientific Law: Statement summarizing repeated
observations (what happens).
- Scientific Theory: Well-tested explanation of phenomena
(why it happens).
- Scientific Model: Representation of a process or object.
- Relationship: Hypotheses → Testing → Theories →
Laws.2.4 Risk and Benefit
- Risk: Probability of harm or loss (e.g., chemical irritates
skin).
- Benefit: Positive outcome or gain (e.g., chemical cleans
effectively).
2.5 Desirability Quotient (DQ)
- Formula: DQ = Benefit / Risk
- Example: Benefit = 8, Risk = 2 → DQ = 4 (more
desirable).
2.6 Basic vs Applied Research
- Basic Research: Fundamental knowledge without
immediate application (e.g., atomic structure).
- Applied Research: Solves practical problems (e.g.,
developing medicines).
2.7 Mass vs Weight, Physical vs Chemical Change, Properties
- Mass: Amount of matter (kg, g). Example: 10 kg rock.
- Weight: Force of gravity (N). Example: 98 N on Earth.
- Physical Change: Alters appearance, not composition.
Example: Ice melting.
- Chemical Change: Alters composition. Example: Iron
rusting.
- Physical Property: Observed without changing substance.
Example: Color, density.
- Chemical Property: Potential chemical change. Example:
Flammability.
2.8 Classify Matter
- State: Solid, Liquid, Gas.- Composition: Element, Compound, Mixture.
- Homogeneity: Homogeneous (uniform) vs Heterogeneous
(not uniform).
2.9 Units and Conversions
- Mass: g, kg; Volume: mL, L, cm³; Length: m, cm, mm.
- Example: 1 m = 100 cm.
2.10 Density, Mass, Volume
- Density = Mass / Volume
- Mass = Density × Volume
- Volume = Mass / Density
- Example: Mass = 50 g, Volume = 10 cm³ → Density = 5
g/cm³
2.11 Heat vs Temperature
- Heat: Total energy of particle motion (Joules).
- Temperature: Average kinetic energy of particles (°C, K,
°F).
2.12 Temperature Scales
- Kelvin = °C + 273.15
- °F = °C × 9/5 + 32
- °C = (°F - 32) × 5/9