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Honors Chemistry

Honors Chemistry. Chapter 1 The Study of Change. 1.1 – 1.2 Chemistry. The study of matter and the changes it undergoes Structure and properties of matter Macroscopic vs Microscopic Structure (microscopic) determines properties (macroscopic). 1.3 Scientific Method.

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Honors Chemistry

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  1. Honors Chemistry Chapter 1 The Study of Change

  2. 1.1 – 1.2 Chemistry • The study of matter and the changes it undergoes • Structure and properties of matter • Macroscopic vs Microscopic • Structure (microscopic) determines properties (macroscopic)

  3. 1.3 Scientific Method • Systematic approach to research • Based on data gathered by observation • Qualitative – general observations • Quantitative – numeric data • Evolution of ideas • Hypothesis – tentative explanation; testable • Theory – unifying principle that explains observations • Scientific Law – mathematical relationship

  4. 1.4 Classification of Matter • Matter – anything with mass and volume • Substance – matter with definite composition and distinct properties • Element – cannot be separated into simpler substances (ie, only one type of atom present) • Examples: aluminum, gold, sulfur, oxygen, neon • Compound – two or more elements chemically combined in fixed proportions • Examples: water, sulfuric acid, rust, baking soda

  5. 1.4 Classification of Matter • Mixture – combination of two or more substances which retain their identities • Homogeneous mixture – composition of mixture is uniform throughout • Examples: saltwater, air, metal alloys • Heterogeneous mixture – composition is not uniform; phase boundaries • Examples: salt and pepper, oil and water, salad dressing

  6. 1.4 Classification of Matter

  7. 1.5 States of Matter sublimation vaporizing melting solid liquid gas condensing freezing deposition

  8. 1.6 Properties of Matter • Physical property • can be observed without changing the identity of the substance • Physical change • remains the same substance • Extensive property • Depends only on the amount of matter present • Intensive property • Depends on the type of matter present

  9. 1.6 Properties of Matter • Chemical property • Property involving reactions with other substances • Chemical change • New substance is produced • Classify the following properties: • Color, mass, flammability, solubility, density • Classify the following changes: • Rusting, cutting, melting, burning, dissolving

  10. 1.7 SI Units • Système Internationale d’Unites • International System of Units

  11. 1.7 SI Conversions

  12. 1.7 SI Conversions m T G M unit d c m n p k h da 3 decimal places 3 decimal places 1 decimal place Multiply number of decimal places by the dimensionality of the unit Some Practice: 0.173 25 000 17.3 cm = ______ m 0.025 kg = ______ mg 986 0.000 058 7 0.986 dm3 = ______ cm3 587 nm = __________ cm

  13. 1.7 Derived Units • Mathematical combinations of base units • Area A=lw m·m = m2 • Volume V = lwh m · m · m = m3 • dm3 = Liter cm3 = mL • Density r = m/V kg/m3, g/cm3, g/mL • Mass vs. Weight • Mass = amount of matter = kg • Weight = force of gravity = N

  14. 1.7 Temperature Scales Fahrenheit Celsius Kelvin Boiling Point 212oF 100oC 373.15 K Human bodytemp = 100oF Freezing Point 32oF 0oC 273.15 K Coldest temp in lab = 0oF Absolute Zero -460oF -273.15oC 0 K

  15. 1.7 Temperature Conversions • Celsius-Kelvin: offset by 273.15o • K = oC + 273.15 • oC = K – 273.15 • Celsius-Fahrenheit • Offset by 32oF • Different sized degrees: 9Fo = 5Co • oC = 5/9 (oF - 32) • oF = 9/5oC + 32 • Convert 98.6oF to oC and to K

  16. 1.8 Scientific Notation • m x 10n • 1 ≤ m < 10 • Exponentiation  multiply exponents • Multiplication  Add exponents • Division  Subtract exponents • Addition/Subtraction  must have same exponent

  17. 1.8 Significant Digits Digits which were actually measured, as opposed to placeholder zeroes Consider...how long is the blue rectangle? 1 2 3 4 5 cm Estimate the next digit Read 2 cm 2.4 cm ± 0.1 cm Let’s use a better ruler uncertainty in measurement dx measurement x Now how long is the rectangle? 2.43 cm ± 0.01 cm Implied ±1 on last digit of all measurements unless told otherwise

  18. 1.8 Significant Digits • Rules of thumb to deal with calculations involving significant digits • Addition/Subtraction • Round to the decimal place of the least precise value • Multiplication/Division • Round to the number of digits of the least precise value • Answers must be rounded properly!

  19. 1.8 Relative Error • Compare uncertainty to measurement • dx RE = ------ x • Often expressed as a percent • With laboratory data, dx is found by comparing experimental result to theoretical expectations • | xth – xexp | RE = --------------- xth

  20. 1.8 Accuracy and Precision • Accuracy • how close a measurement is to the correct value • How close were you to the bull’s eye? • Precision • how closely a set of values agree with each other • Were your shots clustered or scattered? • Let’s measure the bp of water 3 times • Accurate but not precise: 96oC, 101oC, 104oC • Precise but not accurate: 57.2oC, 56.8oC, 57.1oC

  21. 1.9 Dimensional Analysis • Technique for solving problems by treating units of measure as algebraic quantities • Set up conversion factors • 18 in = __________ ft • We know 1 ft = 12 in • 18 in 1 ft------- x -------- = 1 12 in 1.5 ft

  22. 1.9 Dimensional Analysis • Convert the speed of light (3.00 x 108 m/s) to miles / hour. • 3.00 x 108 m 1 km 1 mile 3600 s------------------ x ---------- x ---------- x -------- 1 s 1000 m 1.6 km 1 hr • = 6.8 x 108 mi/hr • 2 sig dig because of km – mile conversion • That wasn’t so bad, was it?

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