Final Exam Review

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• Final Exam Review
• 100 Multiple Choice Questions
• You may use one 3X5 notecard handwritten
• Stoichiometry (12) (mol-mol, mole-mass,
  mass-mass, limiting reactant, yield)
• Gas Laws (21) (Boyles, Charles, Gay-Lussac,
  combined, ideal)
• Solutions (11) (molarity, dissolution,
  kinetic-molecular theory)
• Acid/Base (34) (pH, pOH, concentrations,
  calculations, titration)
• Kinetics/Equilibrium (6)
• Thermochem (5) Nuclear (5) RedOx (6)

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• Final Exam Review
• Stoichiometry
• What do the coefficients in a chemical equation
  represent?
• What do the subscripts represent?
• Know how to identify mole ratios in chemical
  reactions.
• Know how to do mol-mol conversion problems
• Know how to do mol-mass problems
• Know how to do mass-mass problems
• Know how to do limiting reactant problems
• Know how to identify the theoretical yield and
  actual yield
• Know how to calculate yield What does it
  signify

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Calculations

• molar mass
  Avogadros number Grams
  Moles
  particles
• Everything must go through Moles!!!

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Atoms/Molecules and Grams

• How many atoms of Cu are present in 35.4 g of Cu?

35.4 g Cu 1 mol Cu 6.02 X 1023 atoms
Cu 63.5 g Cu 1 mol Cu
3.4 X 1023 atoms Cu
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Mole-Mass Conversions

• Most of the time in chemistry, the amounts are
  given in grams instead of moles
• We still go through moles and use the mole ratio,
  but now we also use molar mass to get to grams
• Example How many grams of chlorine are required
  to react completely with 5.00 moles of sodium to
  produce sodium chloride?
• 2 Na Cl2 ? 2 NaCl

5.00 moles Na 1 mol Cl2 70.90g Cl2
2 mol Na 1 mol Cl2
177g Cl2
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Mass-Mole

• We can also start with mass and convert to moles
  of product or another reactant
• We use molar mass and the mole ratio to get to
  moles of the compound of interest
• Calculate the number of moles of ethane (C2H6)
  needed to produce 10.0 g of water
• 2 C2H6 7 O2 ? 4 CO2 6 H20

10.0 g H2O 1 mol H2O 2 mol C2H6
18.0 g H2O 6 mol H20
0.185 mol C2H6
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Practice

• How many grams of calcium nitride are produced
  when 2.00 g of calcium reacts with an excess of
  nitrogen?
• 3 Ca N2 ? Ca3N2

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Limiting Reactant Example

• 10.0g of aluminum reacts with 35.0 grams of
  chlorine gas to produce aluminum chloride. Which
  reactant is limiting, which is in excess, and how
  much product is produced?
• 2 Al 3 Cl2 ? 2 AlCl3
• Start with Al
• Now Cl2

10.0 g Al 1 mol Al 2 mol AlCl3 133.5 g
AlCl3 27.0 g Al 2 mol Al
1 mol AlCl3
49.4g AlCl3
35.0g Cl2 1 mol Cl2 2 mol AlCl3 133.5 g
AlCl3 71.0 g Cl2 3 mol Cl2
1 mol AlCl3
43.9g AlCl3
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• Final Exam Review
• Gas Laws
• What does the kinetic/molecular theory explain?
• Know what diffusion and effusion are (mixing vs.
  escaping) (examples of each)
• How is pressure (such as in a tire or balloon)
  produced?
• How do you measure atmospheric pressure?
• Know how to convert between pressure units (atm,
  kPa, mmHg, Torr, PSI, etc)
• What is STP what are the values?
• Know how to do Boyles, Charles, Gay-Lussac,
  combined, and ideal gas law problems.

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Collisions cause Pressure

• The pressure of a gas is caused by the collision
  of molecules against the sides of the container.
  The force of the collision against the container
  can be calculated by Newtons Second Law of
  Motion Fma. The F force, mmass in kg
  and a is the acceleration in m/s2.

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Pressure Practice

• Convert the following
• 145 mm Hg into bars
• 450 psi into kPa
• 900 mm Hg into torrs
• 4580 Pa into kPa

• 5. 25 psi into atm
• 6. 150 atm into Pa
• 109 kPa into atm
• 76.9 mm Hg into bars
• 98.6 torr into kPa
• 3 atm into kPa

13
Boyles Law

• Boyles Law states that at constant temperature
  the volume of a fixed amount of gas is inversely
  proportional to its pressure.
• Boyles Law
• P1V1 P2V2

14
Charless Law

• Charless Law states that at constant pressure
  the volume of a fixed amount of gas is directly
  proportional to its absolute temperature.

15
Combined Gas Law Equation

• By combining the equation for Boyles Law and
  Charless Law. We derive the Combined Gas Law
  Equation where

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Standard conditions (STP)

• Remember the following standard conditions.
• Standard temperature 273.15 K
• Standard pressure 1 atm
• At these conditions
• One mole of any gas occupies a volume of 22.4
  liters.

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The ideal gas law

• A combination of Boyles, Charles and Avogadros
  Laws
• PV nRT
• P pressure, atm
• V volume, L
• n moles
• T temperature, K
• R 0.0821 L ? atm/mol ? K
• (gas law constant)

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Example
What is the volume of 2.00 moles of gas at 3.50
atm and 310.0 K? PV nRT V nRT / P
(2.00 mol)(0.08206 L atm K-1mol-1)(310.0 K)
(3.50 atm) 14.5 L
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Diffusion and effusion

• Diffusion
• The random and spontaneous mixing of molecules.
• Effusion
• The escape of molecules through small holes in a
  barrier.
• This is why balloons eventually deflate

20
Kinetic-molecular theory

• This theory explains the behavior of gases.
• Gases consist of very small particles (molecules)
  which are separated by large distances.
• Gas molecules move at very high speeds - hydrogen
  molecules travel at almost 4000 mph at 25oC.
• Pressure is the result of molecules hitting the
  container. At 25 oC and 1 atm, a molecule hits
  another molecule an average of 1010 times/sec.

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• Final Exam Review
• Solutions
• What is an electrolyte? Nonelectrolyte?
• Know about the different solute/solvent mixtures
  (liquid-liquid, gas-liquid, solid-liquid,
  liquid-gas, etc). Be able to identify.
• How can the rate of dissolution be altered?
  (heating, etc.)
• Know difference in dilute, unsaturated,
  saturated, and supersaturated solutions
• How does temperature affect the solubility of
  gases in liquids?
• Know how to do molarity calculations

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• Final Exam Review
• Acid-Base
• Know the properties of acids and bases (taste,
  touch, litmus, pH, reactions)
• What acid is used in car batteries? Which is in
  the stomach? Which is used for explosives?
  Which is in vinegar? Which is the only one that
  can react with glass.
• Know the definitions of the three main acid/base
  descriptions Arrhenius, Bronsted/lowry, Lewis
• Know characteristics of strong acids/bases and
  weak acids/bases
• What is a monoprotic acid? Diprotic? Triprotic?
• Know how to determine conjugate acids and bases

23

• Final Exam Review
• Acid-Base
• Know how to do pH, pOH H, OH-, and titration
  calculations

24

• Final Exam Review
• Thermochem
• What is the definition of heat (energy
  transferred between sample of matter because of a
  difference in their temperatures)
• Know definition of specific heat, heat capacity,
  enthalpy, entropy
• What is the difference between the enthalpies of
  the products and the reactants?
• What is the formula for ?H?

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• Final Exam Review
• Equlibrium
• At equilibrium, how does the forward reaction
  rate compare to the reverse reaction rate?
• What does a low k (lt1) represent? What does a
  high (gt1) k represent?
• Know how to write and equilibrium constant (conc.
  products over conc reactants)
• Le Chateliers How does a change in
  concentration of a reactant or product affect the
  equilibrium? A change in temperature? A change
  in pressure?

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• Final Exam Review
• RedOx
• Know how to assign oxidation numbers
• Know how to identify a redox reaction
• Be able to identify the species being oxidized
  and the one being reduced
• One (simple) balancing problem

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• Final Exam Review
• Nuke
• Know the types of radioactive decay (alpha, beta,
  gamma, positron emission, electron capture)
• Given a radioactive element, be able to complete
  an equation of its decay
• Know penetrating power of alpha, beta, and gamma
  particles
• Know definition of half-life and how to do a
  simple calculation with it.