Concentration Units: Definitions and Uses Molarity (M) mol of - - PDF document

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Concentration Units: Definitions and Uses Molarity (M) mol of - - PDF document

Concentration Units: Definitions and Uses Molarity (M) mol of solute / L of solution solution stoichiometry, Henrys law, osmotic pressure, equilibrium calc Parts by Mass mass of solute / mass of solution e.g. ppm, ppb (% is pph); especially


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1 Concentration Units: Definitions and Uses

Molarity (M) mol of solute / L of solution solution stoichiometry, Henry’s law, osmotic pressure, equilibrium calc Parts by Mass mass of solute / mass of solution e.g. ppm, ppb (% is pph); especially important in environmental Parts by Volume volume of solute / volume of solution used, but not very useful (volume is not additive) Mass per Volume mass of solute / volume of solution important in medicine; in dilute aq soln, g/100mL  %, mg/L  ppm Mole Fraction (X) mol of solute / (mol of solute + mol of solvent) Raoult’s Law Molality (m) mol of solute / kg of solvent freezing point depression, boiling point elevation

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https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spect rpy/nmr/nmr1.htm

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http://scratch.mit.edu/projects/traincode/705416

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https://www.math10.com/en/algebra/probabilities/binomial- theorem/binomial-theorem.html

https://wonderopolis.org/wonder/what-is-pascals-triangle

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5000 10000 15000 20000 25000 30000 35000 40000 45000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 5000 10000 15000 20000 25000 30000 35000 40000 45000 1 2 3 4 5 6 7 8 9 1011121314151617

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Defining a new dependent coordinate (z) in terms of x, the mean, and the standard deviation and plotting y versus z gives the graph on the right.

(p. 70, Harris 8e)

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https://www.chemistry.mcmaster.ca/esam/Chapter_3/section_2.html Radial wavefunction for 1s orbit. Note how amount of electron density decreases in each band out from the nucleus but never reaches zero. https://www.chemistry.mcmaster.ca/esam/Chapter_3/section_2.html

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Three common cases for using the t test to compare measured values:

  • 1. the mean of one sample is compared to a “known” value
  • r established standard

Example: molarity “known” to be 0.1147 M

  • 2. the mean of one sample is compared to the mean of

another sample

Examples: concentration of phenol in Hogtown Creek; average height of CHM 3120 students

  • 3. comparing individual data points in a set of paired

measurements; this approach is commonly used to compare different analytical techniques (p. 78, Harris 8e)

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2 4 6 8 10 12 14 16 57-58 59-60 61-62 63-64 65-66 67-68 69-70 71-72 73-74 75-76

Number of Students Height (inches)

Student Heights, CHM 3120, Spring 2019

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Three common cases for using the t test to compare measured values:

  • 1. the mean of one sample is compared to a “known” value
  • r established standard

Example: molarity “known” to be 0.1147 M

  • 2. the mean of one sample is compared to the mean of

another sample

Examples: concentration of phenol in Hogtown Creek; average height of CHM 3120 students

  • 3. comparing individual data points in a set of paired

measurements; this approach is commonly used to compare different analytical techniques (p. 78, Harris 8e)

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12 175 mg/dL x (1 g/1000 mg) x (10 dL/1L) = 1.75 g/L

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Rank the following solutions in order of increasing pH: 0.1 M HNO2, 0.1 M HNO3, 0.1 M NaNO2, 0.1 M NaNO3, 0.1 M NaOH

  • A. HNO2 < HNO3 < NaNO2 < NaNO3 < NaOH
  • B. HNO3 < HNO2 < NaNO2 < NaNO3 < NaOH
  • C. HNO2 < HNO3 < NaNO3 < NaNO2 < NaOH
  • D. HNO3 < HNO2 < NaNO3 < NaNO2 < NaOH
  • E. HNO3 < HNO2 < NaOH < NaNO3 < NaNO2
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2 4 6 8 10 12 14 10 20 30 40 50 60 70 80 90 100

pH Volume of 0.10 M NaOH added (mL) HCl HNO2

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Rank the following solutions in order of increasing pH: 0.1 M HNO2, 0.1 M HNO3, 0.1 M NaNO2, 0.1 M NaNO3, 0.1 M NaOH

  • A. HNO2 < HNO3 < NaNO2 < NaNO3 < NaOH
  • B. HNO3 < HNO2 < NaNO2 < NaNO3 < NaOH
  • C. HNO2 < HNO3 < NaNO3 < NaNO2 < NaOH
  • D. HNO3 < HNO2 < NaNO3 < NaNO2 < NaOH
  • E. HNO3 < HNO2 < NaOH < NaNO3 < NaNO2
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A 50 mL aliquot of 0.10 M HNO2(aq) is titrated with 0.10 M NaOH(aq) HNO2(aq) + OH(aq)  NO2

 (aq) + H2O(l)

The pKa of HNO2 is 3.15. After 15 mL of OH(aq) is added, the pH will be…

  • A. less than 3.15
  • B. 3.15
  • C. greater than 3.15, but less than 7
  • D. greater than 7, but less than 10.85
  • E. greater than 10.85
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A 50 mL aliquot of 0.10 M HNO2(aq) is titrated with 0.10 M NaOH(aq) HNO2(aq) + OH(aq)  NO2

 (aq) + H2O(l)

The pKa of HNO2 is 3.15. After 70 mL of OH(aq) is added, the pH will be…

  • A. less than 13.00
  • B. 13.00
  • C. greater than 13.00