Honors Chemistry II

Honors Chemistry II Final Review Sheet

The final exam for this class will consist of fifteen (15) multiple-choice questions and three (3) detailed problems. The final exam will cover the following chapters:

Chapter 5: Thermochemistry Chapter 10: Gases and Their Properties Chapter 11: Liquids and Solids Chapter 19: Thermodynamics Chapter 20: Electrochemistry

I will provide any necessary formulas on the final that you will need to do the calculations. It is your responsibility to understand these formulas and how to apply them to various types of problems. Please refer back to your notes and worksheets for additional practice problems.

Chapter 5: Thermochemistry

- Energy: Kinetic and Potential - Temperature and Heat - Three Laws of Thermodynamics - Signs of Energy Change (+ or -) o If surroundings does work on system, ΔE is ______o If system does work on surroundings, ΔE is ______- State Functions with Examples - Expansion and Contraction Work o When is work positive? Negative? (From the system’s point of view) o ΔE is positive, is contraction or expansion taking place? - Enthalpy Definition and Application o ΔH is negative when? ΔH is positive when? - Calorimeter and Heat Capacity o Q = mcΔt - Hess’s Law Definition and Application - Standard Heats of Formation, ΔH° - ΔHproducts - ΔHreactants - Standard Heats of Formation of any Element = ______- Entropy Definition and Application o Positive ΔS occurs when? Negative ΔS occurs when? - Gibbs Free Energy Change: ΔG = ΔH – TΔS (watch your units with J and kJ) - ΔG determination of spontaneity o Spontaneous when ΔG is ______o Nonspontaneous when ΔG is ______

1. Be able to calculate the Gibbs Free Energy Change: ΔG = ΔH – TΔS (UNITS!!!) 2. Understand the difference between a +ΔE and –ΔE… which one means contraction and which one is expansion 3. Understand the difference between +ΔH and –ΔH… which one is exothermic and which one is endothermic 4. Understand the difference between +ΔS and –ΔS… which one is increasing disorder and which one is decreasing the disorder 1 5. Calculation of enthalpy of a reaction: ΔH° = ΔHproducts – ΔHreantants (USE CHART!)

Chapter 10: Gases and Their Properties

- Atmospheric Pressure (different units – atm, kPa, mm Hg, torr) - Gas Laws – what the law describes, how to use the law, and the correct units o Boyles Law o Charles Law o Avogadro’s Law o Ideal Gas Law (using molar mass) – watch UNITS! o Combined Gas Law o Stoichiometric Relationships Among Gases o Dalton’s Law of Partial Pressures o Graham’s Law - Kinetic Molecular Theory (understand the five parts of the theory) - Relationship between the number of moles and pressure - Relationship between the number of moles and volume occupied

Chapter 11: Liquids and Solids

- Dipole Moments (which compounds have it and which do not) o Polar vs. Nonpolar - Electronegativities and Partial Positive and Negative Charges - Intermolecular Forces o Hydrogen Bonding (Understand drawings of H-Bonding) o Dipole-Dipole o London Dispersion Forces (LDF) - London Dispersion Forces and Molecular Weight Relationship - Intermolecular Forces and Boiling Point Relationship - Enthalpy and Entropy Signs Between Different Phases of Matter (Chart) - Heating Curve (Explanation) o Why does it take so much more energy to convert liquid to vapor? - Types of Solids o Amorphous o Crystalline (Descriptions of each) . Ionic . Molecular . Covalent Network . Metallic - Unit Cells in Crystalline Solids o Body - Centered Cubic o Face – Centered Cubic - How many cubes share a common face? A common edge? A common corner? - How many atoms are in Body – Centered Cubic? Face – Centered Cubic? - Phase Diagrams – what they represent - Normal Melting Point – sign of enthalpy and entropy

2 Chapter 19: Thermodynamics

- Spontaneous vs. Nonspontaneous Processes o +ΔG and –ΔG (ΔG = 0 at equilibrium) . Which one favors the reactants? . Which one favors the products? o +ΔS and –ΔS - +ΔH and –ΔH: Which one is exothermic and which one is endothermic? - Definitions of Entropy, Enthalpy, Gibbs Free-Energy - Calculation of Enthalpy of Reaction (ΔH°rxn = ΔH°products – ΔH°reactants) - Calculation of Standard Entropy of Reaction (ΔS°rxn = S°products – S°reactants) - Determination of the sign of entropy, given the reaction o If you increase gas molecules, ΔS is ______o If you decrease gas molecules ΔS is ______o As you go from solid  liquid  gas, entropy ______- Relationship between Entropy and Temperature - Second Law of Thermodynamics o Determination of ΔStotal (ΔStotal = ΔSsystem + ΔSsurroundings) . ΔSsystem . ΔSsurroundings . Watch UNITS among ΔH and ΔS (kJ and J) - Gibb’s Free-Energy Calculations - Temperature determination as to when a reaction will become spontaneous (set ΔG = 0)

Chapter 20: Electrochemistry

- Be able to read and use the Standard Reduction Potential Chart o Keep in mind that this is reduction and if oxidation is occurring, you must switch the sign of E° because you are reversing the reaction from the reduction to oxidation o The strongest agents will have the largest E° value (once signs are switched for oxidation) and vice versa for the weakest agents - Galvanic Cells o Oxidizing Agents o Reducing Agents o Apparatus . Salt Bridge (Purpose of the Salt Bridge) . Anode is where ______occurs . Cathode is where ______occurs . Flow of electrons are from the ______to the ______. Metal Electrodes are needed when… . Drawing of Apparatus including ALL labeling . Balanced Equations for Anode and Cathode o Shorthand Notation for Galvanic Cells (including any electrodes) - Cell Potentials and Free Energy Changes for Cell Reactions o ΔG = -nFE (using cell potential, E, not standard cell potential, E°)

- Standard Cell Potential: E˚ (Negative means…. Positive means…) o Which one is more desirable? Why? 3 - Standard Free Energy Change: ΔG˚ = -nFE˚ (using the standard cell potential, E°) - Standard Cell Potential Calculation Using Reduction Potentials: E˚cell = E˚anode + E˚cathode - Nernst Equation – used to find the cell potential, E, at specific concentrations o E = E° - (0.0592Volts) log Q, where Q = ([Products] / [Reactants]) (n) - Keep in mind that with Q, solids are not included and concentrations are raised to the coefficient numbers - Standard Hydrogen Electrode has a standard cell potential of ______- Arrangement of oxidizing agents and reducing agents in order of increasing strength - Prediction of elements capable of oxidizing other elements (See Notes)

Problems: Chapter 5: Thermochemistry

1. Calculate the standard enthalpy change for each of the following reactions: 4 a. 2SO2(g) + O2(g)  2SO3(g)

b. Mg(OH)2(s)  MgO(s) + H2O(l)

c. SiCl4(l) + 2H2O(l)  SiO2(s) + 4HCl(g)

2. What is the specific heat of water? How many kJ of hear are needed to raise the temperature of 10.00kg of liquid water from 24.6C to 46.2C?

3. Hydrogen gas reacts with oxygen gas to produce gaseous water:

2H2(g) + O2(g)  2H2O(g) ΔH = -483.6kJ

How much heat, in kJ, is released when 2.6g of oxygen react with hydrogen?

4. Using the following reaction, determine how much heat, in kJ, is released when 4.50g methane reacts is burned in presence of oxygen:

CH4(g) + 2O2(g)  CO2(g) + 2H2O(l) ΔH = -890kJ

5. The specific heat of iron is 0.449J/gC. If 28.7g of iron, initially at 33C, absorbs 5.965kJ of heat, what will be the final temperature of the iron?

6. Calculate the enthalpy for the combustion of methane, given the following information:

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) ΔH = -802kJ

2H2O(g)  2H2O(g) ΔH = -88kJ

5 Chapter 10: Gases and Their Properties

1. A sample of nitrogen gas is collected in a 100mL container at a pressure of 688mm Hg and a temperature of 565°C. How many grams of nitrogen gas are present in this sample?

2. Determine the molar mass of a gas that has a density of 2.18g/L at 66°C and 720 mm Hg. Assume a 1L sample.

3. What final temperature in Kelvin is required for the pressure inside an automobile tire to increase from 3.37atm at 10°C to 4.15atm, assuming the volume inside remains constant?

4. What is the density of ammonia in grams/L at STP if the gas in a .750L bulb weighs 0.524g at 32°C and 745mm Hg?

5. To what temperature must 32.0ft3 of a gas at 12°C be heated for it to occupy 100ft3 at the same pressure?

6. A compressed air tank carried by scuba divers has a volume of 8.0L and a pressure of 1.40atm at 20°C. What is the volume of air in the tank in liters at STP?

7. What is the final pressure of a balloon if the initial volume is increased from 125mL at a pressure of 1.11atm to a final volume of 152mL?

6 8. How many grams of XeF6 are required to react with 0.759L of hydrogen gas at 2.67atm and 72°C in the reaction shown below?

XeF6(s) + 3H2(g)  Xe(g) + 6HF(g)

Chapter 19: Thermochemistry 1. Indicate whether each of the following processes produces an increase or decrease in the entropy of the system and then verify your answer by determining the standard molar entropy for each reaction:

a. CO2(s)  CO2(g)

b. CaO(s) + CO2(g)  CaCO3(s)

c. HCl(g) + NH3(g)  NH4Cl(s)

d. 2SO2(g) + O2(g)  2SO3(g)

2. Calculate the standard free energy change for a particular reaction that has a ΔH = 24.6kJ and ΔS = 132J/K at 298K. Is this reaction spontaneous under these conditions?

3. Determine the value of ΔStotal for the following reaction at 25C:

Cu2S(s) + O2(g)  2Cu(s) + SO2(g)

7 Is this reaction spontaneous under these conditions?

Chapter 20: Electrochemistry

1. The standard cell potential for the following galvanic cell is 0.92V:

+3 +3 Al(s) l Al (aq) ll Cr (aq) l Cr(s)

Calculate the standard reduction potential for the chromium half-cell.

2. Consider the following galvanic cell using the following reaction:

+ +2 Zn(s) + 2H (aq)  Zn (aq) + H2(g)

2a. Draw and label this galvanic cell being sure to label ALL parts including the anode, cathode, salt bridge, and electron flow.

2b. Write a balanced equation for the anode and cathode half-reactions.

2c. Provide the shorthand notation for the above reaction

2d. Calculate the standard cell potential, E°

8 + +2 2e. Calculate the cell potential, E, when [H ] = 1.25M, [Zn ] = 0.0250M, and PH2 = 5.5atm.

3. Consider the following galvanic cell:

+ +2 Pb(s) + 2H (aq)  Pb (aq) + H2(g)

3a. Draw and label this galvanic cell being sure to label ALL parts including the anode, cathode, salt bridge, and electron flow.

3b. Write a balanced equation for the anode and cathode half-reactions.

3c. Provide the shorthand notation for the above reaction

3d. Calculate the standard cell potential, E°

3e. Calculate the cell potential, E, when ion concentrations are equal to 0.65M and PH2 is equal to 9.6atm. 9 +2 +2 4. Can Cu oxidize Fe(s)? Can Cu oxidize Ag(s)?