CHEM 1150 Exam 4 Study Guide: States of Matter, Solution Chemistry, and Acids/Bases

Chapter 7: States of Matter and Their Attractive Forces

Gas Laws and Kinetic Molecular Theory (KMT)

The behavior of gases is described by several laws and the Kinetic Molecular Theory, which explains the properties of gases in terms of particle motion.

• Pressure Units: Common units include atmospheres (atm), millimeters of mercury (mmHg), torr, and pascals (Pa). Conversion between units is essential for calculations.

• Kinetic Molecular Theory (KMT): The four main postulates are:

  1. Gases consist of tiny particles in constant, random motion.

  2. Gas particles are far apart relative to their size; most of the volume is empty space.

  3. Collisions between particles and with container walls are elastic (no energy lost).

  4. There are no significant attractive or repulsive forces between particles.

• Ideal Gas Law: Relates pressure, volume, temperature, and moles: $PV = nRT$

• Combined Gas Law: Used when the amount of gas is constant: $\frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2}$

Example: Calculate the final volume of a gas if pressure and temperature change, using the combined gas law.

Intermolecular Forces (IM Forces)

Intermolecular forces are attractions between molecules that influence physical properties.

• London Dispersion Forces: Weak, temporary attractions present in all molecules, especially nonpolar ones.

• Dipole-Dipole Forces: Attractions between polar molecules due to permanent dipoles.

• Hydrogen Bonding: Strong dipole-dipole interaction when H is bonded to N, O, or F.

• Boiling Point (BP): Temperature at which a liquid becomes a gas; higher with stronger IM forces.

• Vapor Pressure: Pressure exerted by vapor above a liquid; lower with stronger IM forces.

• Viscosity: Resistance to flow; higher with stronger IM forces.

Example: Water has a high boiling point due to hydrogen bonding.

Solubility and Biomolecules

• "Like Dissolves Like": Polar solvents dissolve polar solutes; nonpolar solvents dissolve nonpolar solutes.

• Biomolecules: IM forces affect structure and function (e.g., protein folding, DNA base pairing).

Lipids and Cell Membranes

• Fatty Acids: Long hydrocarbon chains with a carboxylic acid group.

• Triglycerides: Glycerol + 3 fatty acids; main storage form of fat.

• Phospholipids: Glycerol + 2 fatty acids + phosphate group; major component of cell membranes.

• Cholesterol: Steroid structure; modulates membrane fluidity.

• Fats vs. Oils: Fats are solid at room temperature (more saturated); oils are liquid (more unsaturated).

Lipid Type	Structure	Function
Fatty Acid	Long hydrocarbon chain, COOH group	Energy storage, building block
Triglyceride	Glycerol + 3 fatty acids	Energy storage
Phospholipid	Glycerol + 2 fatty acids + phosphate	Membrane structure
Cholesterol	Four fused rings	Membrane fluidity, hormone precursor

• Soap, Micelles, Emulsifiers: Amphipathic molecules with both hydrophilic and hydrophobic parts; allow oils and water to mix.

• Lipid Bilayer: Double layer of phospholipids forms the cell membrane; hydrophobic tails inside, hydrophilic heads outside.

Example: Soap molecules form micelles to trap grease in water.

Chapter 8: Solution Chemistry—Sugar and Water Do Mix

Types of Mixtures and Definitions

Solutions are homogeneous mixtures of two or more substances.

• Solution: Homogeneous mixture at the molecular level.

• Solute: Substance dissolved (present in lesser amount).

• Solvent: Substance doing the dissolving (present in greater amount).

• Aqueous: Solution where water is the solvent.

• Colloid: Mixture with intermediate particle size; scatters light (Tyndall effect).

• Suspension: Heterogeneous mixture; particles settle out over time.

• Saturated: Contains maximum amount of solute at given temperature.

• Unsaturated: Contains less than the maximum solute.

Type	Particle Size	Appearance	Separation
Solution	<1 nm	Clear	No separation
Colloid	1-1000 nm	Cloudy	By centrifuge
Suspension	>1000 nm	Cloudy	Settles out

Example: Salt water is a solution; milk is a colloid; muddy water is a suspension.

Properties of Water and Solubility

• Water: Excellent solvent due to polarity and hydrogen bonding.

• Solubility: Gases are more soluble at lower temperatures; solids are more soluble at higher temperatures.

• Henry's Law: The solubility of a gas in a liquid is proportional to its pressure above the liquid. $C = kP$

Electrolytes and Dissociation

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

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

• Nonelectrolyte: Does not dissociate (e.g., sugar).

Example Dissociation Equations:

• Strong: $\mathrm{NaCl} \rightarrow \mathrm{Na}^+ + \mathrm{Cl}^-$

• Weak: $\mathrm{CH_3COOH} \rightleftharpoons \mathrm{CH_3COO}^- + \mathrm{H}^+$

• Nonelectrolyte: $\mathrm{C_6H_{12}O_6} \rightarrow \text{no ions}$

Concentration Units and Calculations

• Percent Composition:

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

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

  • Mass/volume (m/v): $\% = \frac{\text{g solute}}{\text{mL solution}} \times 100$

• ppm: $\frac{\text{mg solute}}{\text{kg solution}}$

• ppb: $\frac{\text{\mu g solute}}{\text{kg solution}}$

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

• Dilution: $C_1 V_1 = C_2 V_2$

Example: To prepare 250 mL of 0.5 M NaCl from 1.0 M stock, use $(1.0)(V_1) = (0.5)(0.250)$ to solve for $V_1$.

Membranes and Transport

• Semipermeable Membrane: Allows certain molecules to pass (e.g., water) but not others.

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

• Diffusion: Movement of particles from high to low concentration.

• Isotonic: Equal solute concentration inside and outside cell.

• Hypotonic: Lower solute concentration outside; cell swells (hemolysis).

• Hypertonic: Higher solute concentration outside; cell shrinks (crenation).

• Osmotic Pressure: Pressure required to stop osmosis.

• Active Transport: Movement against gradient, requires energy.

• Facilitated Transport: Uses proteins to move substances down gradient.

• Passive Diffusion: Movement without energy input.

Chapter 9: Acids, Bases, and Buffers in the Body

Definitions and Theories

• Arrhenius Acid: Produces H+ in water.

• Arrhenius Base: Produces OH– in water.

• Brønsted-Lowry Acid: Proton (H+) donor.

• Brønsted-Lowry Base: Proton (H+) acceptor.

Theory	Acid	Base
Arrhenius	H+ producer	OH– producer
Brønsted-Lowry	H+ donor	H+ acceptor

Strong Acids and Bases

• Strong Acids (memorize 7): HCl, HBr, HI, HNO3, HClO4, HClO3, H2SO4

• Strong Bases (memorize 8): Group 1 and 2 hydroxides (e.g., NaOH, KOH, Ca(OH)2, etc.)

Naming Acids

• hydro-ic acid: For binary acids (e.g., HCl: hydrochloric acid)

• -ic acid: For polyatomic ions ending in -ate (e.g., HNO3: nitric acid)

• -ous acid: For polyatomic ions ending in -ite (e.g., HNO2: nitrous acid)

Neutralization and Equilibrium

• Neutralization: Acid + base → salt + water. With carbonates, CO2 is also produced.

• Equilibrium Constant (Keq): $K_{eq} = \frac{[\text{products}]}{[\text{reactants}]}$

• Comparing K Values: Larger K means more products at equilibrium.

• Le Châtelier’s Principle: System shifts to counteract changes in concentration, temperature, or pressure.

Acid Dissociation and pH Calculations

• Weak Acid Dissociation: $\mathrm{HA} + \mathrm{H_2O} \rightleftharpoons \mathrm{H_3O}^+ + \mathrm{A}^-$

• Acid Dissociation Constant (Ka): $K_a = \frac{[\mathrm{H_3O}^+][\mathrm{A}^-]}{[\mathrm{HA}]}$

• Conjugate Acid-Base Pairs: Differ by one H+.

• Autoionization of Water: $\mathrm{H_2O} + \mathrm{H_2O} \rightleftharpoons \mathrm{H_3O}^+ + \mathrm{OH}^-$

• $K_w = 1.0 \times 10^{-14}$ at 25°C

• pH Calculation: $\mathrm{pH} = -\log [\mathrm{H}^+]$

• $[\mathrm{H}^+][\mathrm{OH}^-] = 1.0 \times 10^{-14}$

Example: Calculate pH if [H+] = 1.0 × 10–3 M: pH = 3.

Additional info: Where the original notes listed only keywords or brief points, full academic explanations, definitions, and examples have been added for clarity and completeness.