General Chemistry I: Exam Study Guide (GOB Chemistry Topics)

General Chemistry I: Key Concepts and Practice Problems

Introduction

This study guide summarizes essential topics in General, Organic, and Biological (GOB) Chemistry, as reflected in a typical college-level exam. It covers foundational concepts, problem-solving strategies, and example questions relevant to the following chapters: gases, solutions, chemical reactions, acids and bases, equilibrium, and related calculations.

Chemistry and Measurements

Units, Constants, and Conversions

• SI Units: Standard units for mass (kg), length (m), volume (L), and amount (mol).

• Key Constants:

  • Avogadro's number: $N_A = 6.022 \times 10^{23}$ particles/mol

  • Gas constant: $R = 0.0821$ L·atm/(mol·K)

• Conversion Factors: 1 atm = 760 mmHg = 101.3 kPa; 1 L = 1000 mL

Matter and Energy

Physical Properties of Matter

• Density: $\text{Density} = \frac{\text{mass}}{\text{volume}}$

• Specific Heat: $q = mc\Delta T$

Gases

Gas Laws and Calculations

• Ideal Gas Law: $PV = nRT$

• STP Conditions: Standard Temperature and Pressure (0°C, 1 atm); 1 mol gas = 22.4 L

• Partial Pressure: $P_{\text{total}} = P_1 + P_2 + \ldots$

• Kinetic Molecular Theory: Gas molecules move rapidly in random directions; average kinetic energy is proportional to temperature in Kelvin.

Example: Calculating the mass of O2 gas at STP using molar volume and molar mass.

Solutions

Solubility, Concentration, and Solution Behavior

• Solubility: Amount of solute that dissolves in a given amount of solvent at a specific temperature.

• Saturated Solution: Contains the maximum amount of solute at equilibrium.

• Concentration (Molarity): $M = \frac{\text{moles of solute}}{\text{liters of solution}}$

• Solubility Rules: Most Group 1A and ammonium salts are soluble; most nitrates are soluble; most chlorides, bromides, and iodides are soluble except with Ag+, Pb2+, Hg22+.

Example: Using a solubility graph to determine if a solution is saturated or unsaturated at a given temperature.

Chemical Reactions and Quantities

Types of Reactions and Stoichiometry

• Balanced Chemical Equation: Shows the reactants and products with correct stoichiometric coefficients.

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

• Stoichiometry: Use mole ratios from the balanced equation to calculate masses or volumes of reactants and products.

Example: Calculating the mass of product formed from given amounts of reactants using mole ratios.

Acids and Bases

Properties and Strengths

• Strong Acid: Completely ionizes in water (e.g., HCl, HNO3).

• Weak Acid: Partially ionizes in water (e.g., HF, acetic acid).

• Conjugate Acid-Base Pairs: Acids donate protons (H+), bases accept protons.

Example: Identifying strong and weak acids and predicting the extent of ionization in solution.

Chemical Equilibrium

Dynamic Equilibrium and Equilibrium Expressions

• Dynamic Equilibrium: Forward and reverse reactions occur at equal rates; concentrations remain constant.

• Equilibrium Constant ($K_c$): $K_c = \frac{[\text{products}]}{[\text{reactants}]}$ (raised to the power of their coefficients)

Example: Writing the equilibrium expression for the formation of ammonia: $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$

Reaction Rates and Energy

Activation Energy and Endothermic/Exothermic Reactions

• Activation Energy: Minimum energy required for a reaction to occur.

• Exothermic Reaction: Releases heat; products have lower energy than reactants.

• Endothermic Reaction: Absorbs heat; products have higher energy than reactants.

Example: Interpreting energy diagrams to determine reaction type and activation energy.

Practice Table: Solubility Guidelines

Compound Type	Solubility
Group 1A, NH4+ salts	Soluble
Nitrates (NO3-)	Soluble
Chlorides, Bromides, Iodides	Soluble (except Ag+, Pb2+, Hg22+)
Sulfates (SO42-)	Soluble (except Ba2+, Pb2+, Ca2+, Sr2+)
Carbonates, Phosphates	Insoluble (except Group 1A, NH4+)

Additional info:

• Practice problems and exam-style questions are included to reinforce understanding of key concepts.

• Refer to the periodic table for atomic masses and element identification.

• Equation sheets provide essential formulas and constants for calculations.