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Russo Sch. Chemistry Semester II Review
Ch. 8: ChemQuest #30 (Intro to Moles), ChemQuest #31a, #31b (% composition & empirical formulas), hydrate
labs, ChemQuest #32 (Intro to Stoich), ChemQuest #33 (LR) and ChemQuest #34 (% yield)
 1 mole = 6.022x1023 particles (molecules, ions, …)
 calculate molar mass & use molar mass to convert between grams and moles
 % composition, empirical formulas (smallest ratio of elements in a compound) & molecular formulas
o Cryolite, a mineral used in making glass & porcelain is composed of 32.85% sodium, 12.85%
aluminum and 54.30% fluorine and has a molar mass of about 420g/mole. What is its formula?
 assume 100g of material  32.85g Na, 12.85g Al and 54.30g F
 change g to moles: 1.429 mol Na, 0.4763 mol Al & 2.858 mol F
 divide by whichever element has the fewest # of moles (Al) – this is the mole ratio 3 Na : 1
Al : 6 F – Na3AlF6
 Na3AlF6 has a molar mass of 210g/mol. Cryolite has a molar mass of 420g/mol.
 420/210 = 2 so cryolite has a formula of 2(Na3AlF6) or Na6Al2F12
 Using a balanced equation to calculate the amounts of substances involved in a chemical reaction.
 Limiting reagent (the reactant that will make the least amount of product)
o Sulfuric acid (H2SO4) reacts with aluminum hydroxide by double replacement. If 30.0 g of sulfuric
acid react with 25.0 g of aluminum hydroxide which is the limiting reagent?
 Balance the equation: 3 H2SO4 + 2 Al(OH)3  Al2(SO4)3 + 6 H2O
 Divide moles of reactants by the balancing coefficient; smallest answer is LR
⁄


H2SO4
⁄
H2SO4 has the smallest answer so H2SO4 must be limiting.
% yield =
Chapter 9: ChemQuest 29 (Reduction & Oxidation)
 activity series (book calls this the EMF (electromotive force) series
o if the single element is more reactive (higher on the activity series) a rxn will occur
 hydrogen + nickel (II) oxide  rxn will Not occur – H2 is less reactive than Ni
 potassium iodide + chlorine  rxn will occur – Cl2 is more reactive than iodine
 Write balanced half-reactions for reduction and oxidation.
o Reduction occurs when an atom or ion gains electrons: Cl + 1e-  Cl-.
o Oxidation occurs when an atom or ion loses electrons: 2 P-3  2 P + 6e- .
o In a reaction, the number of electrons lost will equal the number of electrons gained.
 Identify the element that is being reduced, the element that is being oxidized, the reducing agent and the
oxidizing agent.
o OIL RIG: oxidiation is loss of electrons, reduction is gain of electrons
o the element being reduced is the oxidizing agent
o the element being oxidized is the reducing agent
 ♪♫“It starts at the anode, electrons are lost there. They go through the wire to the load that is on fire. They
enter the cathode and reduce the cations. The anions go through the salt bridge back to where?” ♫
 Identify cathode and anode of an electrochemical cell.
 Identify direction of electron flow
 Calculate cell potentials and use them to determine spontaneity of synthesis and decomposition reactions.
Chapter 11: ChemThink: Behavior of Gases, ChemQuest #36 – Gases and Moles and ChemQuest #37 – Gas
Stoichiometry
 Kinetic molecular theory (chemthink concepts), pressure, volume & temp relationships of gases
 Kelvin temperatures = Celsius + 273.15 All gas laws MUST use temperatures in Kelvin!

combined gas law:
P1V1 P2V2

, Ideal gas law: PV = nRT, Dalton’s law: PT = P1 + P2 + …
T1
T2

Gas stoichiometry
o use balanced equation to predict liter ratios as needed (since moles & liters are proportional for
gases)
 ex. H2 + Cl2  2 HCl so

at STP 1 mole = 22.4 liters so at STP
Chapter 12 – Molarity packet & ChemQuest #39b (Dilution)
 solution = homogeneous mixture: salt water, air, steel alloy
 solute – present in smaller amount; solvent – present in greater amount
 Calculate concentration: molarity (M) = moles of solute / liter of solution
 Use molarity in stoichiometry problems
 Dilution: M1V1 = M2V2 (NOT intended for situations in which a chemical reaction is occurring. Just
when adding water to dilute a stronger concentration down to a weaker molarity).
 colligative properties – properties that depend on the amount of material present, not its identity (boiling
point elevation, freezing point depression)
o
Tb =
o
Tf =
Chapter 15 – ChemQuest # 48 (Intro to Acids & Bases), ChemQuest #49 (pH and pOH)
 Naming acids and bases (actually chapter 5 p. 197-198 & 202)
 identify Arrhenius & Brønsted-Lowry acids & bases, conjugate acids & bases
 strong acids & bases (ionize or dissociate completely, very large equilibrium constant, strong electrolyte),
weak acids & bases (incomplete ionization, very small equilibrium constant, weak electrolyte)
 pH of acids typically ranges from 07, bases from 714, pH of 7 = neutral although negative pH’s and
pH’s above 14 are possible
 pH + pOH = 14
 pH = -log [H3O+]
 pOH = - log [OH-]
 [H3O+][OH-] = 1 x 10-14
 buffers are solutions that resist pH change
 essential in:
o buffered medicines (Bufferin…)
o enzymes
o dyeing
o your body’s pH chemistry
o fermentation
Organic Chemistry
 alkanes, alkenes & alkynes (2n+2, 2n & 2n-2)
 trends in boiling points
o more carbon atoms = higher bp
o more branching = lower bp
o presence of dipole (OH group) = higher bp
 naming & drawing isomers
 functional groups from the chart
 condensation reactions (alcohol & carboxylic acid form ester & water)
Nuclear
 alpha, beta +, beta –, electron capture and gamma decay
 fission & fusion