Exam 2 Study Guide: Nuclear Chemistry, Stoichiometry, Gas Laws, Solutions, and Acids & Bases

Chapter 5: Nuclear Chemistry

Types of Radiation and Nuclear Decay

Nuclear chemistry studies the changes in atomic nuclei, including radioactive decay and nuclear reactions. Understanding the types of radiation and their properties is essential for safety and applications.

• Alpha Decay (α): Emission of an alpha particle (2 protons, 2 neutrons). Low penetration; stopped by paper or skin.

• Beta Minus Decay (β-): Emission of an electron. Moderate penetration; stopped by plastic or glass.

• Beta Plus Decay (β+): Emission of a positron. Similar penetration to beta minus.

• Gamma Decay (γ): Emission of high-energy photons. High penetration; requires lead or thick concrete for shielding.

Protection: Alpha particles are most dangerous if ingested; gamma rays are most dangerous to be near due to high penetration.

Half-Life and Nuclear Activity

• Half-Life (t1/2): Time required for half of a radioactive sample to decay.

• Activity: Rate of decay, measured in becquerels (Bq) or curies (Ci).

$N = N_0 \left( \frac{1}{2} \right)^{t/t_{1/2}}$

Radiation Effects and Safety

• 100-500 rad: Radiation sickness.

• >500 rad: Lethal exposure.

Fusion and Fission

• Fusion: Combining light nuclei to form a heavier nucleus (e.g., hydrogen fusion in stars).

• Fission: Splitting a heavy nucleus into lighter nuclei (e.g., uranium fission in reactors).

Isotopes

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

Chapter 7: Stoichiometry

Types of Chemical Reactions

Stoichiometry involves the quantitative relationships in chemical reactions. Recognizing reaction types is fundamental for predicting products and balancing equations.

• Combination/Synthesis: Two or more substances form one product.

• Decomposition: One substance breaks into two or more products.

• Single Replacement: One element replaces another in a compound.

• Double Replacement: Exchange of ions between two compounds.

• Combustion: Substance reacts with O2, producing CO2 and H2O.

• Acid-Base Neutralization: Acid reacts with base to form salt and water.

• Redox Reactions: Involve transfer of electrons. LEO the lion goes GER: Loss of Electrons is Oxidation; Gain of Electrons is Reduction.

Balancing Chemical Equations

• Atoms are rearranged, not created or destroyed.

• Equations must be balanced to obey the Law of Conservation of Mass.

Mole Concept and Calculations

• Mole: Amount of substance containing Avogadro’s number ($6.022 \times 10^{23}$) of particles.

• Molar Mass: Mass of one mole of a substance (g/mol).

$\text{Moles} = \frac{\text{grams}}{\text{molar mass}}$

$\text{Mole Ratio}$ from balanced equation is used for conversions between reactants and products.

Energy in Reactions

• Exothermic: Releases heat.

• Endothermic: Absorbs heat.

Chapter 8: Gas Laws

Kinetic Theory of Gases

The kinetic theory explains the behavior of gases in terms of particle motion, energy, and collisions.

• Gases consist of small particles in constant, random motion.

• Collisions are elastic; energy is conserved.

• Volume of particles is negligible compared to container.

Gas Properties and Laws

• Pressure (P): Force per unit area exerted by gas particles.

• Volume (V): Space occupied by gas.

• Temperature (T): Average kinetic energy of particles (in Kelvin).

Boyle’s Law

At constant temperature, pressure and volume are inversely related.

$P_1 V_1 = P_2 V_2$

Charles’ Law

At constant pressure, volume and temperature are directly related.

$\frac{V_1}{T_1} = \frac{V_2}{T_2}$

Gay-Lussac’s Law

At constant volume, pressure and temperature are directly related.

$\frac{P_1}{T_1} = \frac{P_2}{T_2}$

Combined Gas Law

Relates pressure, volume, and temperature.

$\frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2}$

Avogadro’s Law

Equal volumes of gases at same temperature and pressure contain equal numbers of molecules.

$\frac{V_1}{n_1} = \frac{V_2}{n_2}$

Dalton’s Law of Partial Pressures

Total pressure is the sum of partial pressures of each gas in a mixture.

$P_{\text{total}} = P_1 + P_2 + \ldots$

Applications

• Breathing: Involves changes in lung volume and pressure, following gas laws.

• Kinetic Energy vs. Heat Energy: Kinetic energy is energy of motion; heat is energy transfer due to temperature difference.

Chapter 9: Solutions

Types of Solutions

Solutions are homogeneous mixtures of two or more substances. They can be solid, liquid, or gas.

• Solid Solutions: Alloys (e.g., brass).

• Liquid Solutions: Saltwater (NaCl in H2O).

• Gas Solutions: Air (O2 and N2).

Solvent vs. Solute

• Solvent: Substance present in greater amount; dissolves the solute.

• Solute: Substance dissolved in the solvent.

Concentration Calculations

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

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

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

Osmosis and Tonicity

• Osmosis: Movement of solvent through a semi-permeable membrane from low to high solute concentration.

• Hypertonic Solution: Higher solute concentration than cell; cell shrinks.

• Hypotonic Solution: Lower solute concentration than cell; cell swells.

• Isotonic Solution: Equal solute concentration; no net movement of water.

Colloids and Suspensions

• Colloid: Medium-sized particles; scatter light; do not settle (e.g., milk).

• Suspension: Large particles; settle out (e.g., muddy water).

• Solutions: Small particles; do not settle or scatter light.

Type	Particle Size	Settling	Filterability	Example
Solution	<1 nm	No	No	Saltwater
Colloid	1-1000 nm	No	No (but not through semi-permeable membrane)	Milk
Suspension	>1000 nm	Yes	Yes	Muddy water

Chapter 10: Acids and Bases

pH and Its Meaning

pH measures the hydrogen ion concentration in a solution. It indicates acidity or basicity.

$pH = -\log_{10}[H^+]$

• pH < 7: Acidic

• pH = 7: Neutral

• pH > 7: Basic

Naming Common Acids and Bases

• Acids: HCl (hydrochloric acid), H2SO4 (sulfuric acid), HNO3 (nitric acid), CH3COOH (acetic acid).

• Bases: NaOH (sodium hydroxide), KOH (potassium hydroxide), Ca(OH)2 (calcium hydroxide), NH3 (ammonia).

Acid-Base Neutralization

• Acid reacts with base to produce salt and water.

$\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}$

Carbonates as Bases

• Carbonates (e.g., Na2CO3) react with acids to produce H2CO3, which decomposes into H2O and CO2 gas.

$\text{CO}_3^{2-} + 2H^+ \rightarrow H_2CO_3 \rightarrow H_2O + CO_2 \uparrow$

Example: Reaction of sodium carbonate with hydrochloric acid produces sodium chloride, water, and carbon dioxide gas.

Additional info: The above notes expand on the study guide points with definitions, equations, and examples for clarity and completeness.