Example Final Conceptual Questions
- Page ID
- 306159
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Topical Questions: (these should be mastered so that you can answer them quickly without thinking)
Thermodynamics
- What is the difference between a “microstate” and a “macrostate”?
- Explain the concept of entropy
- Explain why is an isothermal expansion of an ideal gas is spontaneous when the change in internal energy is zero
- Can the absolute zero of entropy be determined?
- How does increasing temperature affect the entropy of a system? Why?
- What has the higher entropy, liquid water or water vapor? Why?
- What has the higher entropy, \(NO (g)\) or \(NO_2 (g)\)?
- What is the second law of thermodynamics?
- What characterizes a spontaneous reaction?
- Why do we introduce Gibbs free energy?
- What is ΔG at equilibrium?
- What drives a chemical reaction?
- Why are some reactions spontaneous only at high temperatures while others are spontaneous only at low temperatures?
- What is the definition of the free energy of formation?
- What does the sign of the standard free energy of a compound tell you?
- What is the standard state?
- How does ΔGº relate to ΔG at nonstandard conditions?
- Explain how the equilibrium constant and Gibbs energy are related
- What is the temperature dependence of K?
- For each of these processes state if they are endothermic or exothermic, cause an increase or a decrease in entropy, and whether the process occurs spontaneously. Not all of them has unique answers, describe what the answers will depend on
- Condensation of a gas to a liquid
- Dissolution of an ionic solid
- Mixing of water and oil
- Mixing of water and ethanol
- Melting of an ice cube
- \(H_2 (g) + O_2 (g) → H_2O (l)\)
- Isothermal expansion of an ideal gas
Liquids, Solids, and Intermolecular Forces
- Define the following terms
- Cohesive forces (forces between like molecules)
- Adhesive forces (forces between unlike molecules)
- Surface tension
- Viscosity
- Classify IMFs into one of four categories
- Permanent electrostatic-Permanent electrostatic
- Permanent Electrostatic-Induced electrostatic
- Spontaneous Electrostatic-Induced Electrostatic (Dispersion)
- Repulsion
- Define Polarizability
- What IMF category(ies) does polarizability play a strong role in?
- What factors influence the magnitude of polarizability?
- What is the difference between London force and Dispersion force?
- Under what conditions will hydrogen bonding be observed?
- How do the IMFs strengths compare to covalent bonding strengths?
- What is the origin of the repulsion force?
- In what systems are repulsion forces not involved?
- Which IMF has the longest range of interaction (be specific)?
- Which IMF has the shortest range of interaction (be specific)?
- What is a hydrogen bond donor?
- What is a hydrogen bond acceptor?
- Give two examples of phases that do not correspond to differing states.
- What is the definition of vapor pressure?
- How is vapor pressure related to IMFs?
- What is the definition of boiling?
- What are two ways that you can make a liquid boil?
- Define
- critical point
- triple point
- melting
- melting point
- enthalpy of fusion
- heat of fusion
- enthalpy of vaporization
- heat of vaporization
- enthalpy of sublimation
- heat of sublimation
- Supercritical fluids
- Phase transitions
- How is ·Enthalpy of vaporization related to ·Enthalpy of sublimation?
- What is the origin of this relationship?
- What are the differences between the phase diagram for water and for \(\ce{CO2}\)?
- When would you use the Claussius-Clapeyron equation?
- When would you use the Clapeyron equation?
- What is the difference between the two? What is the approximation used to derive the Claussius-Clapeyron equation?
Solutions
- What are the definitions of the following concentration units:
- Mass percent?
- ppm?
- Mole fraction?
- Molarity?
- Molality?
- Which concentration units are temperature dependent?
- Which concentration units are temperature independent?
- What determines if the enthalpy of solution is positive or negative?
- What is an ideal solution?
- What drives the formation of an ideal solution?
- Crystal lattice energies are typically very strong. Give two reasons why many salts nevertheless are easily soluble in water
- How does the solubility of gases depend of the partial pressure of the gas?
- What is the definition of a lattice energy?
- What is the definition of a Solvation energy?
- Definition between real and ideal solutions
- Definition of Activities
- How does the vapor pressure of an ideal solution depend on composition?
- Is the composition of the vapor phase and liquid phase for a solution different? Why?
- What is fractional distillation? How does it work?
- What is an azeotrope?
- What is osmotic pressure?
- What is reversed osmosis?
- What are colligative effects? Which four did we discuss in class?
- Using a phase diagram, explain how freezing point depression and boiling point elevation are consequences of Raoult’s law
- What is the van ’t Hoff factor?
- What is Henry's law?
- Is it applicable for ideal solutions?
- What is Raoult's law?
- Is it applicable for ideal solutions
- Is Raoult's law applicable for volatile or non-volatile solutions? Or both or neither?
- What is the definition of a saturated solution?
- What does supersaturated mean?
- Does a solid have a vapor pressure?
- Is vaporization an endothermic or an exothermic process?
Equilibria
- What is a dynamic equilibrium? How does it compare to static equilibria?
- What is the law of mass action?
- What is the definition of \(K_c\)?
- What are the units of \(K_c\)?
- How does the equilibrium constant depend on the initial conditions?
- What is the activity?
- If a reaction can be written as the sum of two reactions with known equilibrium constants, how can you determine the equilibrium constant for the overall reaction?
- What is \(K_p\)?
- What is the difference between \(K_p\) and \(K_c\)?
- How do pure liquids and pure solids enter the equilibrium constant? Why?
- What can you tell from the size of the equilibrium constant?
- What is the difference between K and Q?
- How can you predict the direction of a reaction knowing K and Q?
- If you add more reactant to a reaction that is initially at equilibrium, what will happen?
- If you increase the partial pressures equally of all gases involved in a reaction that is initially at equilibrium, what will happen?
- According to Le Chatelier’s principle, what happens to an exothermic reaction if the temperature is increased? Does K change?
- If Q >K reaction, does the reaction (as written) go to the left, right or not change?
- If Q <K reaction, does the reaction (as written) go to the left, right or not change?
- If Q =K reaction, does the reaction (as written) go to the left, right or not change?
Acids and Bases
- Is an aqueous solution of NaCl acidic or basic? Why?
- Is an aqueous solution of NH4Cl acidic or basic? Why?
- What is the pH of a solution containing 0.1 M HCl and 0.1 M acetic acid? What is the concentration of acetic acid and acetate (the conjugate base) in this solution?
- What is a buffer solution?
- How do you make a buffer solution?
- What is the pH of a buffer solution?
- What is the buffer capacity? What does it depend on?
What characterizes an acid-base indicator ?- What is the equivalence point in a titration?
- What is pH halfway to the equivalence point during a titration of a weak base with a strong acid?
- How are pH and pOH related?
- How is the pKa of an acid related to the pKb of the conjugate base?
- What is pH for a 0.1M solution of HNO3?
- What is pH for a 10-8 M solution of HNO3?
- What defines a strong acid?
- Name three strong acids
- Which one is the stronger acid: Acetic acid (pKa= 4.74) or formic acid (pKa= 3.74)?
- Which one is the stronger base: the acetate ion (\(C_2H_3O_2^−\)) or formate ion (\(CHO_2^−\))?
- When can you simplify the solution of an equilibrium calculation (by assuming that the change x is small)?
Solubility
- What is the definition of the solubility product?
- How does the solubility product relate to the solubility defined in chapter 13?
- How do you determine if precipitation occurs in a solution?
- What is the common-ion effect?
Explain why the solubility of a sparingly soluble salt increases when a highly soluble salt of spectator ions is added to the solution?What is “salting out”?Give one explanation for why “salting out” occurs- What is the activity coefficient?
Why is Ksp not constant?What is fractional precipitation?For what types of salts is the solubility affected by pH?