GOB Chemistry Study Guide: Gases, Solutions, Acids & Bases, and Organic Compounds (Ch. 8.4–11.4)

Chapter 8: Gases

Gas Laws and Properties

The behavior of gases is described by several fundamental laws that relate pressure, volume, temperature, and amount. Understanding these laws is essential for predicting and calculating gas properties in chemical systems.

• Standard Pressure: 1 atm = 760 mm Hg

• Temperature: Must be in Kelvin for gas law calculations. Formula: $T(\text{K}) = T(\degree C) + 273$

• Gay-Lussac's Law: Relates pressure and temperature at constant volume. Formula: $\frac{P_1}{T_1} = \frac{P_2}{T_2}$

• Avogadro's Law: Relates volume and amount of gas at constant temperature and pressure. Formula: $\frac{V_1}{n_1} = \frac{V_2}{n_2}$

• Standard Temperature and Pressure (STP): 1 atm (760 mm Hg) and 0°C (273 K)

• Partial Pressure: The pressure exerted by each gas in a mixture. Dalton's Law of Partial Pressures: $P_{\text{total}} = P_1 + P_2 + \ldots$

Example: Calculate the total pressure of a mixture containing oxygen and nitrogen using Dalton's Law.

Chapter 9: Solutions

Solubility and Solution Types

Solutions are homogeneous mixtures of solute and solvent. Understanding solubility, concentration, and solution types is crucial for predicting chemical behavior in biological and chemical systems.

• Solubility: Ability of a substance to dissolve in a solvent. Use solubility rules to predict if a compound will dissolve.

• Types of Solutions: Isotonic, hypertonic, and hypotonic solutions affect water movement across membranes.

• Osmosis: Movement of water across a semipermeable membrane from low to high solute concentration.

• Concentration Units:

  • Mass Percent (m/m): $\%\,\text{(m/m)} = \frac{\text{mass of solute}}{\text{mass of solution}} \times 100$

  • Molarity (M): $M = \frac{\text{mol of solute}}{\text{L of solution}}$

  • Volume Percent (v/v): $\%\,\text{(v/v)} = \frac{\text{volume of solute}}{\text{volume of solution}} \times 100$

• Dilution: Calculating new concentration after dilution. Formula: $C_1V_1 = C_2V_2$

Example: Calculate the molarity of a solution prepared by dissolving 5 g NaCl in 250 mL water.

Chapter 10: Acids and Bases & Equilibrium

Acid-Base Theories and Calculations

Acids and bases are classified by their ability to donate or accept protons. Understanding their properties and calculations is essential for predicting chemical reactions and biological processes.

• Arrhenius Definition: Acids produce $H^+$ in water; bases produce $OH^-$.

• Brønsted-Lowry Definition: Acids donate protons ($H^+$); bases accept protons.

• Conjugate Acid-Base Pairs: Every acid has a conjugate base and vice versa.

• Strong vs. Weak Acids/Bases: Strong acids/bases dissociate completely; weak acids/bases do not.

• pH and pOH Calculations:

  • pH: $\text{pH} = -\log[H^+]$

  • pOH: $\text{pOH} = -\log[OH^-]$

  • Relationship: $\text{pH} + \text{pOH} = 14$

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

• Equilibrium: Use Le Châtelier’s Principle to predict shifts in equilibrium.

Example: Calculate the pH of a solution with $[H^+] = 1 \times 10^{-4}$ M.

Chapter 11: Introduction to Organic Chemistry: Hydrocarbons

Naming and Structure of Organic Compounds

Organic compounds are classified based on their structure and functional groups. Systematic naming (IUPAC) allows chemists to communicate molecular structures clearly.

• Recognizing Organic vs. Inorganic Compounds: Organic compounds contain carbon and hydrogen, often with other elements.

• IUPAC Naming Steps:

  1. Identify the longest carbon chain (parent chain).

  2. Number the carbon atoms from the end nearest a substituent.

  3. Specify the location and name of each substituent (alphabetical order).

  4. Name the main chain and add prefixes for substituents.

• Prefixes for Number of Carbons: Meth-, Eth-, Prop-, But-, etc.

• Types of Hydrocarbons: Alkanes (single bonds), cycloalkanes (rings), branched alkanes.

• Physical Properties: Melting point, boiling point, solubility, and physical state depend on structure.

Number of Carbons	Prefix
1	meth-
2	eth-
3	prop-
4	but-
5	pent-
6	hex-
7	hept-
8	oct-
9	non-
10	dec-

Example: Name the compound CH3CH2CH3 (propane).

Additional info: Academic context and explanations have been expanded for clarity and completeness. Table 11.2 referenced in the notes has been recreated with standard prefixes for 1–10 carbons.