Welcome to AP Chemistry:

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• Welcome to AP Chemistry
• A college course taught in high school

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• Cellphone NO!!!!
• Tues-Friday (A and B week)
• Safety Contract
• AUP
• SHOES IN LOCKER!!!!!
• Need to Buy
• Scientific Calculator
• Sewn Notebook (I will provide, Write in pen)

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Measuring
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Measuring
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Measuring
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Measuring
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Measuring
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• Warm-Up Group the following
• Au H2O O2
• C P4 P2O5
• Be N2 C2H4
• C60 NH3 Cl2
• Te S8 C6H12O6

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The Key to the Universe
Mixtures
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Elements

• Definition - Elements contain only one type of
  atom
• 90 naturally occurring elements
• Transuranium elements
• Types of elements
• a) Monoatomic C, Fe, Au
• b) Diatomic H2, N2, O2, F2, Cl2, Br2, I2
• c) Polyatomic P4, C60

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Compounds

• Definition - Composed of two or more different
  elements
• Examples
• H2O, CH4, NaCl, Fe2(SO4)3
• Are there more elements or compounds?
• Elements letters
• Compounds - words

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Pure Substances

• Have definite unchanging properties
• Contain only one type of element or compounds
• Examples
• Pure Gold
• Pure Water

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Metric

• 1. SI System Le System International dUnites
• 2. Base ten scale
• 1000 m 1 km
• 100 m 1 hm
• 10 m 1 dam
• 1 m 1 m
• 1 m 10 dm
• 1 m 100 cm
• 1 m 1000 mm

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Metric

• Standard Units
• Length meter
• Mass kilograms
• Time second

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Metric

• Base Units
• Length meter
• Volume liter
• Mass grams
• Time second
• Energy Joules

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Metric

• Factor Label method
• 55 cm ? m
• 0.055 L ? mL
• 0.00456 km ? cm
• 550 cm2 ? m2
• 25 miles/hr ? m/s

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Metric

• 129 hrs ? Days
• 0.468 m?km
• 825 cm ? in
• 0.0023 L ? mL
• 0.468 m ? mm
• 1245 cm ? km
• 55 mi/hr ? km/hr
• 55 mi/hr ? m/min

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Metric

• 129 hrs ? Days 5.38 days
• 0.468 m?km 0.000468 km
• 825 cm ? in 325 in
• 0.0023 L ? mL 2.3 mL
• 0.468 m ? mm 468 mm
• 1245 cm ? km 0.01245 km
• 55 mi/hr ? km/hr 89 km/hr
• 55 mi/hr ? m/min 1500 m/min

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Other Measurements

• 475 nm ? m
• 1 nm 1 X 10-9 m
• 1 X 109 nm 1 m
• 475 nm 1 X 10-9 m
• 1 nm
• 28 mL ? L (1mL 1 X 10-6 L
• 28 mL ? mL

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Temperature
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Temperature

• Conversion Formulas
• F 1.8 (oC) 32
• K C 273
• C K 273

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Temperature

• Ex 24 oC ? oF
• 48oF ? oC
• 177 K ?oC

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Temperature

• Absolute Zero
• All atomic and molecular motion stops
• Coldest possible temperature
• Never reached absolute zero
• Liquid Nitrogen 77 K (-196 oC)
• Dry Ice 216 K (-56.6 oC)

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Temperature

• 102 oF ? oC
• -10.0 oC ? oF
• 25 oC ? K
• 177 K ? oC
• 310 oC ? K

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Temperature

• 102 oF ? 39oC
• -10.0 oC ? 14.0 oF
• 25 oC ? 298 K
• 177 K ? -96 oC
• 310 oC ? 583 K

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Temperature

• 25 oC ? oF
• 50 oF ? K
• 310 K ? oC
• 10 K ? oC
• -15 oC ? K

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Temperature

• 25 oC ? 77 oF
• 50 oF ? 283 K
• 310 K ? 37 oC
• 10 K ? -263 oC
• -15 oC ? 258 K

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Accuracy and Precision

• Dartboard example
• Accuracy how close the average of a set of
  measurements is to the true value
• Precision How close a set of measured values
  are to one another
• Always want to compare your experiments with a
  textbook value

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Error Analysis

• Percent Error Measure of accuracy
• Error Experimental Accepted X 100
• Accepted
• NOTE Experimental average of all trials

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Error Analysis Example 1

• A student measures the density of a sample of
  copper at 8.75 g/mL. The accepted value is 8.96
  g/mL. Calculate the percent error.

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Error Analysis Example 2

• A student measures the melting point of a sample
  of beryllium at 667 oC. The accepted value is
  649 oC. Calculate the percent error.

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Error Analysis Range

• Range - Measure of precision
• Range highest trial lowest trial
• Example 1
• A student measures the melting point of a sample
  of beryllium and does four trials (667 oC, 645
  oC, 670 oC, 655 oC). Calculate the range and
  comment on precision.

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Error Analysis Range

• Example 2
• A student measures the density of a sample of
  lead and does four trials (11.3, 10.5, 11.9, 10.8
  g/cm3). Calculate the range and comment on
  precision.

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Error Analysis

• Example 3
• Using the numbers in the previous example,
  calculate percent error. The accepted density of
  lead is 11.4 g/cm3.

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Accuracy and Precision

• Students did trials to measure the density of a
  metal. The accepted density is 7.2 g/cm3. Were
  they accurate or precise?
• Set 1 7.21 7.25 7.18
• Set 2 6.40 7.90 7.30
• Set 3 6.45 6.52 6.48

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Significant Figures

• 1. Def - All of the measured values plus one
  estimated place
• 2. Ruler example (6.55 cm)
• 3. Indicator of the precision of a measurement
• GPA 3.872 vs 3.870
• Grades 95 vs 95.4

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Numbers with a Decimal

• 1. Always include a decimal if you can
• 2. All whole numbers plus any zeroes to the right
  Dot right
• 3. How many sig figs? Also, write in sci.
  notation
• 3.44 cm 60.001 cm
• 430.0 cm 0.0032 cm
• 0.00320 cm

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Numbers without a Decimal

• 1. Often poor measurements
• 2. Examples Not left
• 18,500 people 120 apples

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Numbers without a Decimal

• How many sig figs? Also, write in scientific
  notation
• 10,500 cm 240 cm
• 120,000 cm 4 cm
• 45 cm

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Significant Figures

• How many significant figures are in the
  following? Also, write the numbers in proper
  scientific notation.
• 1508 cm 20.003 lb
• 300 ft 300.0 ft
• 0.00705 m 0.007050 m
• 1250 1250.
• 1250.0

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Significant Figures

• Round the following to three sig figs
• 32.45
• 0.0067530
• 0.003904
• 11,980

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Significant Figures and Math

• 1. When doing math, your answer is only as good
  as your worst measurement.
• 2. Example
• 15.00 mL
• 14.2 mL
• 3. Round AFTER you do the math.

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Significant Figures and Math

• Addition/Subtraction Rule - Keep the least number
  of decimal places.
• Examples
• 7.56 0.375 14.2203 22.16
• 0.0327 0.00068 0.0320

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Significant Figures and Math

• Multiplication/Division Rule Answer contains
  the least of TOTAL significant figures
• Examples
• 2.34 X 3.225

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Significant Figures and Math

• 11.688 ? 4.0
• 7 X 7
• 4.68 X 1016 ? 9.1 X 10-5

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Significant Figures and Math

• 1. Multiple Operations Round when you change
  between add/sub and mult/div
• 2. Examples
• (0.56 X 11.73) 22.34
• (6.5688) 22.34
• (6.6) 22.34 28.9
• (12.45 11.643) X 2.68

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Significant Figures and Math

• 160 X 3.445
• 19.64 0.466
• 4.856 X 1010?2.0 X 102
• (16.44 ? 2.33) 22.3

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Absolute Numbers

• 1. Also called exact numbers
• 2. Have an infinite number of significant figures
• 3. Counting numbers and values in definitions.
• 4. Examples
• 24 students Diameter 2r
• 1 km1000m
• 5. NEVER use exact numbers for determining sf.

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Absolute Numbers

• Suppose we divide 1.66 lbs of candy among 3
  people?
• (Ans 0.553 lbs/person)
• What is the diameter of a circle whose radius is
  3.845 m?
• (Ans 7.690 m)

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Density

• Formula D mass/volume
• Often used in chemistry for liquids
• 100 mL of water is heavier than 100 mL of alcohol
  (draw scale)
• Density is an intensive property.

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• What is the density of mercury if 100.0 g
  occupies a volume of 7.36 cm3. (Ans 13.6
  g/cm3)
• What mass of mercury is in 65.0 cm3? (Ans 884
  g)
• What volume of ethanol is needed to provide 15.0
  g of ethanol? The density 0.789 g/mL. (Ans
  19.0 mL)

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• 24.
• 63.5 mL.
• 6.5 ms
• 0.95 mm
• 4.23 mm3
• 4.23 mL
• 0.35 ng
• 6.54 ms