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  • Z5e 8 Table 1.1
  • Z5e 9 Table 1.2 (summarized)
  • Z5e 23 Fig. 1.9 & SE 1.10
  • Z5e 25 Section 1.8 Density
  • 105.8 g
  • 361 lbs + 75.0 lbs = 436 lbs (rounded)

Ch1 z5e chem fnd Ch1 z5e chem fnd Presentation Transcript

  • Welcome to AP Chemistry pp
  • Ch. 1 Significant figures
    • Meaningful digits in a MEASUREMENT
    • Exact numbers are counted , have unlimited significant figures
    • If it is measured or estimated, it has sig figs.
    • If not it is exact . . .
    • All numbers except zero are significant.
    • Some zeros are, some aren’t
  • Which zeroes count? pp
    • In between other sig figs does
    • Before the first number doesn’t
    • After the last number counts if
    • it is after the decimal point
    • the decimal point is written in
    • 3200 2 sig figs
    • 3200 . 4 sig figs
  • Which zeroes count?
    • Atlantic Pacific Rule
    • Decimal point P resent, use P acific Ocean
    • E.g., 0.002540
    • Decimal point A bsent, use A tlantic Ocean
    • E.g., 2540
  • Doing the math pp
    • Multiplication and division, same number of sig figs in answer as the least in the problem
    • Addition and subtraction, same number of decimal places (vs. sig figs) in answer as least in problem.
  • More Preliminaries Scientific Method Metric System Uncertainty
  • Scientific method.
    • A way of solving problems
    • Observation - what is seen or measured
    • Hypothesis - educated guess of why things behave the way they do. (possible explanation)
    • Experiment - designed to test hypothesis
    • leads to new observations,
    • and the cycle goes on
  • Scientific method.
    • After many cycles, a broad, generalizable explanation is developed for why things behave the way they do.
    • This is a Theory
    • Also, a regular pattern of how things behave the same in different systems emerges.
    • This is a Law
    • Laws are summaries of observations
  • Scientific method.
    • Theories have predictive value.
    • The true test of a theory is if it can predict new behaviors.
    • If the prediction is wrong, the theory must be changed.
    • Theory is the why
    • Law is the how
  • Observations Hypothesis Experiment Prediction Experiment Modify Law Theory (Model)
  • Metric System
    • Every measurement has two parts:
    • Number
    • Scale (unit)
    • SI system (le Systeme International) is based on the metric system.
    • Prefix + base unit
    • Prefix tells you the power of 10 to multiply by - decimal system - easy conversions
  • Metric System
    • Base Units
    • Mass - kilogram (kg)
    • Length - meter (m)
    • Time - second (s)
    • Temperature - Kelvin (K)
    • Electric current- ampere (amp, A)
    • Amount of substance - mole (mol)
  • Prefixes pp
    • Giga - G 1,000,000,000 10 9
    • mega - M 1,000,000 10 6
    • kilo - k 1,000 10 3
    • deci - d 0.1 10 -1
    • centi - c 0.01 10 -2
    • milli - m 0.001 10 -3
    • micro - m 0.000001 10 -6
    • nano - n 0.000000001 10 -9
  • Deriving the Liter
    • Liter is defined as the volume of 1 dm 3
    • gram is the mass of 1 cm 3
    • 1 ml = 1 cm 3
  • Figure 1.3 Measurement of Volume
  • Mass and Weight
    • Mass is measure of resistance to change in motion
    • Weight is force of gravity.
    • Sometimes used interchangeably
    • Mass can’t change, weight can
  • Uncertainty
    • Basis for significant figures
    • All measurements are uncertain to some degree
    • Precision - how repeatable
    • Accuracy - how correct - closeness to true value.
    • Random error - equal chance of being high or low - addressed by averaging measurements - expected
  • Figure 1.4 Common Types of Laboratory Equipment Used to Measure Liquid Volume
  • Figure 1.6 Measurement of Volume Using a Buret The volume is read at the bottom of the liquid curve (called the meniscus ).
  • Uncertainty
    • Systematic error - same direction each time
    • Want to avoid this
    • Better precision implies better accuracy
    • you can have precision without accuracy
    • You can’t have accuracy without precision
  • Figure 1.7 The Difference between Precision and Accuracy
  • Dimensional Analysis Using the units to solve problems
  • Dimensional Analysis
    • Use conversion factors to change the units
    • Conversion factors = 1
    • 1 foot = 12 inches (equivalence statement)
    • 12 in = 1 = 1 ft. 1 ft. 12 in
    • 2 conversion factors
    • multiply by the one that will give you the correct units in your answer.
  • Examples
    • 11 yards = 2 rod
    • 40 rods = 1 furlong
    • 8 furlongs = 1 mile
    • The Kentucky Derby race is 1.25 miles. How long is the race in rods, furlongs, meters, and kilometers?
    • A marathon race is 26 miles, 385 yards. What is this distance in rods, furlongs, meters, and kilometers?
  • Examples
    • Science fiction often uses nautical analogies to describe space travel. If the starship U.S.S. Enterprise is traveling at warp factor 1.71, what is its speed in knots?
    • Warp 1.71 = 5.00 times the speed of light
    • speed of light = 3.00 x 10 8 m/s
    • 1 knot = 2000 yd/h exactly
    • Apothecaries (druggists) use the following set of measures in the English system:
    • 20 grains ap = 1 scruple (exact)
    • 3 scruples = 1 dram ap (exact)
    • 8 dram ap = 1 oz. ap (exact)
    • 1 dram ap = 3.888 g
    • 1 oz. ap = ? oz. troy
    • What is the mass of 1 scruple in grams?
    Examples
  • Examples
    • The speed of light is 3.00 x 10 8 m/s. How far will a beam of light travel in 1.00 ns?
  • Temperature and Density
  • Temperature
    • A measure of the average kinetic energy
    • Different temperature scales, all are talking about the same height of mercury.
    • Derive a equation for converting ºF toºC
  • 0ºC 32ºF 0ºC = 32ºF
  • 100ºC 212ºF 100ºC = 212ºF 0ºC 32ºF 0ºC = 32ºF
  • 100ºC 212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF
  • 100ºC 212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF 1ºC = (180/100)ºF 1ºC = 9/5ºF
  • ºC ºF
  • ºC ºF (0,32)= (C 1 ,F 1 )
  • ºC ºF (0,32) = (C 1 ,F 1 ) (120,212) = (C 2 ,F 2 )
  • Celsius/Fahrenheit Conversions
    • Y - intercept is at 32 degrees F
    • T c = 5/9(T f - 32)
    • T f = (9/5 x T c ) + 32
  • Figure 1.8 The Three Major Temperature Scales
  • Figure 1.9 Normal Body Temperature on the Fahrenheit, Celsius, and Kelvin Scales
  • Density
    • Ratio of mass to volume
    • D = m/V
    • Useful for identifying a compound
    • Useful for predicting weight
    • An intrinsic property- does not depend on what the material is
  • Density Problem
    • An empty container weighs 121.3 g. Filled with carbon tetrachloride (density 1.53 g/cm 3 ) the container weighs 283.2 g. What is the volume of the container?
  • Density Problem
    • A 55.0 gal drum weighs 75.0 lbs. when empty. What will the total mass be when filled with ethanol? density 0.789 g/cm 3 1 gal = 3.78 L 1 lb = 454 g
  • Matter: Anything occupying space and having mass.
  • Classification of Matter
    • Three States of Matter:
      • Solid: rigid - fixed volume and shape
      • Liquid: definite volume but assumes the shape of its container
      • Gas: no fixed volume or shape - assumes the shape of its container
  • Types of Mixtures
    • Mixtures have variable composition.
    • A homogeneous mixture is a solution (for example, vinegar)
    • A heterogeneous mixture is, to the naked eye, clearly not uniform (for example, a bottle of ranch dressing)
  • Pure Substances
    • Can be isolated by separation methods:
    •  Chromatography
    •  Filtration
    •  Distillation
  • Figure 1.10 Simple Laboratory Distillation Apparatus
    • Element: A substance that cannot be decomposed into simpler substances by chemical means.
    Compound: A substance with a constant composition that can be broken down into elements by chemical processes.
  • Figure 1.13 The Organization of Matter