Analytical Chemistry 1

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Analytical Chemistry 1

• Harris Chapters 1 and 2

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Key Terminology

• Qualitative Analysis
• Quantitative Analysis
• Analyte
• Sample (noun and verb)
• Aliquot
• Determination (and determine)
• Calibration
• Homogeneous
• Heterogeneous
• Interference

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Usage

• I will be conducting a quantitative analysis on
  an aliquot from my cow poop sample to determine
  the concentration of selenium.
• A Twinkie? is heterogeneous. By dissolving it in
  solvent, and mixing, a homogeneous sample was
  created from which an aliquot was taken for
  analysis. Alternatively, the creamy center and
  cake portions could have been analyzed
  separately.
• My calibration scheme was designed to account for
  the effects of any interferences which would
  impact the analytical results.

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Using Spreadsheets in Analytical Chemistry

• Review this section.
• Note the hints/shortcut tear out after page 12!
• Do all graphs with EXCEL!
• Do all regression analyses with EXCEL!

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Units.

• Fundamental SI Units
• Meters (m)
• Kilograms (kg)
• Time (s)
• Temperature (K)
• Quantity (mol)
• Electric Current (A)

• Derived SI Units
• Frequency (Hz, s-1)
• Pressure (Pa, N/m2)
• Charge C
• Electric Potential (V)
• Force (N)

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Unit Conversions
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Unit Prefixes
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Dimensional Analysis (math with units)

• Units in mathematical operations cancel out.
• If you have setup the problem and the units
  cancel correctly, youre right 99 of the time!
• How much lead is there in 1 liter of a 99 ppm
  lead solution (ppm ug/mL)?
• Cancel out the units just as you would with
  numerical values! I expect this is how you will
  do problems!

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Common Units..

• Molarity (M) moles of analyte/L of solution
• Molality (m) moles of analyte/kg of solvent
• Weight Percent (mass percent, wt or WT)
• (mass of analyte/mass of sample)100
• Volume Percent (volume of solute/volume of
  solution) x 100

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• Parts Per Million (ppm)
• Weight based unit
• Interchangeable in aqueous solutions
• VERY COMMON in environmental work
• Since the density of water is very close to 1
  g/mL, and dilute aqueous solutions are primarily
  water, this approximation applies for most
  aqueous solutions.
• For solids and dilute aqueous solutions
• ppm mg/kg

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• Parts Per Billion (ppb)
• Weight based unit
• Interchangeable in aqueous solutions
• Also VERY COMMON in environmental work
• Since the density of water is very close to 1
  g/mL, and dilute aqueous solutions are primarily
  water, this approximation applies for most
  aqueous solutions.

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Example Calculations.

• Do your calculations this way so your work is
  shown and I can give partial credit! Replicate
  calculations only need to be shown the first
  time!
• What is the molar mass of NaCl?

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A correctly written balanced equation!

• You will always be expected to..
• Identify the conjugate acid/base pairs and/or
• Identify the oxidizing agent and reducing agent
  and/or
• Identify the precipitate.
• A solution of sodium chloride is mixed with a
  solution of lead (II) nitrate. Write a complete
  balanced and net ionic equation for what occurs.
• NaCl, Pb(NO3)2, lead (II) chloride is insoluble

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Analytical Tools
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• How many grams of calcium (III) nitrate are
  needed to make 2.0 L of a solution that is 1.0 M
  in nitrate ion? What is the concentration of
  nitrogen in this solution in ppm?