Chemistry Tutorial
Introduction:
Senior Chemist – Barbara Beatty MSc
Senior Chemist - Dawit Teclemariam PhD
Chemist Administrator – Paul Vinik MSc
Topics Discussed:
1) pH
2) Resistivity
3) Chloride Concentration Measurements
4) Carbonate Concentration Measurements
5) Sulfate Concentration Measurements
Periodic Table of Elements – By Dmitri Mendeleev 1869
•Valences
•Metals
•Transition Metals
•Reactivity
•Metalloids
•Main Group Elements
•Noble Gases
•Nonmetals
•Atomic Number
Electron Orbital Theory
Reaction Mechanisms:
1) Covalent - Organics
2) Ionic – Sharing of
electrons
3) Hydrogen Bonding – H2O
Reactivity:
1) Full Shell – Inert gas
2) Distance from Nucleus
makes it easier to share
electrons
3S2
2P6
2S2
1S2
Nucleus
pH
• pH = the negative log of the
hydronium ion concentration.
• pH= -Log[H3O]+
Definitions:
Buffer – A solution characterized by the ability to resist changes in
pH when limited amounts of acid or base are added to it.
Acid – A substance that when dissolved in water increases the
hydrogen ion concentration. The proton Donor.
Base – A substance that when dissolved in water increases the
Hydroxyl Ion concentration. The Proton Acceptor.
0
7
Acidic
Neutral
14
Basic
Alkaline
Neutral Solution: [H3O+] = [OH-]
Acidic Solution: [H3O+] > [OH-]
Ionic
Dissociation:
+
-
• H2O  [H3O ] + [OH ]
+
2-
• H2SO4  2 [H ] + [SO4 ]
+
-
• HCl  [H ] + [Cl ]
+
-
• NaOH [Na ] + [OH ]
pH Tutorial:
http://www.chem.ubc.ca/courseware/pH/index.html
Resistance
• Ohm’s Law: R = V / I
• Resistance (R) – The ratio of the voltage applied to the
current that flows through a material.
• Resistivity (ρ ):
• Conductivity (σ): σ = 1/ρ
The conductivity of a solution is related to the
dissolved ion concentration, or Ionic Strength.
Chloride Ion Concentration
Chloride Ion [Cl-] concentration can be measured with
numerous instrumentation and chemical methods. The
most common technique is titration. Titration is used by
most common pool water test kits as well as FM 5-552.
AgNO3 + NaCl + K2CrO4AgCl + Ag2CrO4 + KNO3 + NaNO3 + KCl
By adding silver nitrate drop wise to an aqueous
solution, the product, silver chloride precipitates as a
white solid. When there is no more chloride left to make
silver chloride, the product becomes silver chromate and
this transition is observed as a color shift toward redbrown.
Sulfate Ion Concentration
Na2SO4 + BaCl2  BaSO4 + 2NaCl
Barium sulfate is insoluble in water and subsequently
precipitates. By waiting 5 to 10 minutes, the gases in
the sample are allowed to escape, but the solids are
not given enough time to settle out suspension. After
5 minutes a turbidity measurement is used to assess
the quantity of suspended solids.
Carbonate Content
CaCO3 + HCl  CaCl2 + H2CO3
Hydrochloric acid is added to calcium carbonate and calcium
chloride and carbonic acid are formed. The products are placed
in a filtration funnel and carbon dioxide evolves while the soluble
calcium chloride permeates through the filter. By burning the
ash free filter paper, the change in mass from the original
sample is due to the loss of carbonates.
CO2
CaCl2 + H20 + CO2
After Filtration, burn
the filter paper and
contents. Compare
initial weight with
final to determine
carbonate content.