160 likes | 294 Views
Zumdahl’s Chapter 1. Chemical Foundations. Chemistry : “The Science of All that’s Matter” Theory and Experiment System é Internationale and English Units Notation and Multipliers Error Analysis Dimensional Analysis Temperature. Extensive Properties E.g., E kin = ½ mv 2
E N D
Zumdahl’s Chapter 1 Chemical Foundations
Chemistry: “The Science of All that’s Matter” Theory and Experiment Systemé Internationale and English Units Notation and Multipliers Error Analysis Dimensional Analysis Temperature Extensive Properties E.g., Ekin = ½ mv 2 Intensive Properties E.g., = m / V Classification of Matter Mixtures Compounds Elements Subatomic Chapter Contents
CHEMISTRY:The Science of All that’s Matter • From subatomic to macroscopic properties • From static to dynamic properties • From shape to functionality • From electronic forces to molar energetics • Synthesis, Analysis, Characterization & Utility • Interactions of Matter with Matter andLight • Understanding Environmental Consequences
Observations Eternal Reproducible Importance of Records! Inferences Implications leading to new experiments to confirm or deny both inferences and theories Explanations Tentative Consistent with all observations! Suggest new experiments Paradigms Shifted by inconsistencies Laws of Nature Impotence postulates Occam’s Razor Experiment and Theory
Systéme International Units • MASS, the kilogram [ kg ] • LENGTH, the meter [ m ] • TIME, the second [ s ] • COUNT, the mole [ mol ] or NAv = 6.0221023 • TEMPERATURE, the Kelvin [ K ] • ENERGY, the Joule [ J ] = 1 kg m2 s-2 • FORCE, the Newton [ N ] = 1 J m-1
Scientific Notation and Multipliers • Dealing with the very small and the very large • Scientific Notation: ± 9.999 10 ±99 • Addition & Subtraction need common powers. • Multiplication & Division: exponents add & subtract. • Scale units with Multipliers ( often by 10 ±3n ) • 10+12Tera- 10+9Giga- 10+6Mega- 10+3kilo- • 10-1deci- 10-2centi- 10-3milli- 10-6icro-
Error Analysis • Repeated experimental values differ. • If tightly clustered, they are PRECISE. • If their average falls near the correct value, they are ACCURATE. • Quoted as average value± uncertainty () with units! • ~2/3 fall within of avg • Exact numbers have zero uncertainty, e.g., 1 cal 4.184 J
Significant Figures • Rules of Thumb: • Multiplication & Division • Use the smaller number of significant figures • Addition & Subtraction • Use the least significant digit of largest magnitude • Zeroes count as significant figures? • Captive & trailing zeroes count; leading don’t. • y = f(x1,x2,…) and y2 = Xn2 (f / xn)2
Dimensional Analysis • Add and subtract common units only! • Under multiplication and division, units accumulate with + and – powers, respectively. • Solution sought must have units identical with that accumulation, or it is not correct. • Factor method of unit conversion chains: • [ 102 cm / 1 m ]3 [ 1 L / 103 cm3 ] or 1 m3 = 103 L
Temperature • SI unit the Kelvin [ K ] • Because 0 K is absolute • 0°C = + 273.15 K • 0 K = – 273.15°C • Different origin but the same size units. • TF = 32°F + (9°F/5°C) TC • 0 K = – 459.67 °F • 98.6 °F = ? °C
Extensive Properties • Scale with the AMOUNT or COUNT • Mass and number of moles are obviously extensive. • Volume and energies so scale extensive. • Temperature is not extensive! • 2 hot bricks have twice the energy but not twice the temperature of one
Intensive Properties • Remain the same under increases in amount or count. Temperature is intensive. • Density, = m / V, is the ratio of two extensive variables; so the amount cancels and is intensive.
Phases of Matter • Condensed Phases “incompressible” • SOLID, maximally compacted & immobile • LIQUID, molecules not fixed but fluid yet still adjacent to one another; of fixed density • Rarified Phases “compressible” • GAS, fluid but nonadjacent molecules expand to fill containers completely (by varying density) • PLASMA, hot, ionized gas of charged atoms & electrons
MIXTURES Separable by physical means E.g., filtration or chromatography Heterogeneous Components in different phases or domains Homogeneous Components in same phase and domain COMPOUNDS Compounded of different elements, but these can be separated chemically ELEMENTS Identical building blocks, atoms, react identically. SUBATOMIC MATTER Protons, neutrons, and electrons Classifications of Matter