General Chemistry 101: Final Exam Study Guide

L the General Chemistry 101: Final Exam Study Guide

Section 1: Chemical Nomenclature and Formulas

This section covers the writing of chemical formulas for acids and ions, which is fundamental for understanding chemical reactions and solution chemistry.

• Acids and Ions: Acids are substances that release hydrogen ions (H+) in solution. Their formulas often start with H.

• Examples:

  • /: HBrO4

Application: Correctly naming and writing formulas is essential for predicting reaction products and balancing equations.

Section 2: Gases and Gas Laws

This section involves calculations related to gases, including partial pressures and the behavior of gases under different conditions.

• Key Concepts:

  • Partial Pressure: The pressure exerted by a single gas in a mixture. Dalton's Law states that the total pressure is the sum of the partial pressures of all gases present.

  • Ideal Gas Law: $PV = nRT$

• Example: Calculating the percent of argon in a light bulb at a given temperature and pressure.

Section 3: Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.

• Equilibrium Constant (K): Expresses the ratio of product concentrations to reactant concentrations at equilibrium.

• Relationship between Kc and Kp: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is the change in moles of gas.

• Example: Calculating $K_{eq}$ for a reaction using thermodynamic data.

Section 4: Acid-Base Equilibria and Buffers

This section focuses on buffer solutions, pH calculations, and the use of the Henderson-Hasselbalch equation.

• Buffer Solutions: Solutions that resist changes in pH upon addition of small amounts of acid or base.

• Henderson-Hasselbalch Equation: $pH = pK_a + \log\left(\frac{[A^-]}{[HA]}\right)$

• Example: Calculating the pH of a buffer before and after addition of strong acid or base.

Section 5: Thermochemistry

Thermochemistry deals with the heat changes that accompany chemical reactions.

• Enthalpy Change ($\Delta H$): The heat absorbed or released at constant pressure.

• Hess's Law: The total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps.

• Example: Calculating $\Delta H$ for a reaction using given thermochemical equations.

Section 6: Atomic Structure and Isotopes

This section covers the structure of atoms, including protons, neutrons, electrons, and isotopes.

• Key Terms:

  • Isotope: Atoms of the same element with different numbers of neutrons.

  • Atomic Number (Z): Number of protons in the nucleus.

  • Mass Number (A): Total number of protons and neutrons.

Symbol	Protons	Neutrons	Electrons	Net Charge
Fe2+	26	30	24	+2
Zn	30	35	30	0
Al3+	13	14	10	+3
Cl-	17	18	18	-1

Section 7: Properties of Matter

Understanding the difference between state functions and extensive properties is crucial in thermodynamics.

• State Function: A property that depends only on the current state of the system, not on the path taken (e.g., enthalpy, entropy).

• Extensive Property: A property that depends on the amount of matter present (e.g., mass, volume).

• Intensive Property: Independent of the amount of matter (e.g., temperature, density).

Section 8: Electrolytes

Electrolytes are substances that conduct electricity when dissolved in water. They are classified as strong or weak based on their degree of ionization.

• Strong Electrolyte: Completely dissociates in solution (e.g., NaCl).

• Weak Electrolyte: Partially dissociates in solution (e.g., acetic acid, CH3COOH).

Section 9: Stoichiometry and Limiting Reactants

Stoichiometry involves the calculation of reactants and products in chemical reactions, including limiting reactant and percent yield problems.

• Limiting Reactant: The reactant that is completely consumed first, limiting the amount of product formed.

• Percent Yield: $\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$

Section 10: Redox Reactions and Balancing Equations

Redox (reduction-oxidation) reactions involve the transfer of electrons. Balancing these reactions, especially in basic solution, is a key skill.

• Oxidizing Agent: Substance that gains electrons (is reduced).

• Reducing Agent: Substance that loses electrons (is oxidized).

• Balancing in Basic Solution: Add OH- ions to both sides as needed after balancing in acidic solution.

Section 11: Thermodynamics and Spontaneity

Thermodynamics predicts whether a reaction will occur spontaneously based on enthalpy, entropy, and free energy changes.

• Gibbs Free Energy: $\Delta G = \Delta H - T\Delta S$

• Spontaneity: A reaction is spontaneous if $\Delta G < 0$.

• Equilibrium: At equilibrium, $\Delta G = 0$.

Section 12: Acids, Bases, and pH Calculations

Calculating the pH and pOH of solutions is essential for understanding acid-base chemistry.

• pH: $pH = -\log[H^+]$

• pOH: $pOH = -\log[OH^-]$

• Relationship: $pH + pOH = 14$ at 25°C

Section 13: Useful Constants and Equations

Key constants and equations are provided for reference in calculations.

• Gas Constant (R): $0.08206\ \text{L·atm·mol}^{-1}\text{·K}^{-1}$ or $8.314\ \text{J·mol}^{-1}\text{·K}^{-1}$

• Avogadro's Number: $6.022 \times 10^{23}$

• Standard Temperature and Pressure (STP): 1 atm and 0°C

• Quadratic Formula: $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$

• Key Equations:

  • $PV = nRT$

  • $pH = -\log[H^+]$

  • $K_p = K_c(RT)^{\Delta n}$

  • $\Delta G = \Delta H - T\Delta S$

  • $\Delta G = -nFE_{cell}$

  • $\Delta G = -RT\ln K_{eq}$

Additional info:

• This study guide covers topics from multiple chapters of a standard General Chemistry course, including chemical nomenclature, stoichiometry, thermochemistry, equilibrium, acid-base chemistry, atomic structure, and thermodynamics.

• Sample calculations and equations are provided to support problem-solving on exams.