General Chemistry 2: Intermolecular Forces

Review Materials in General Chemistry 2 (Second Semester)

• Liquids, Solids, and Gases (KMT): Liquids have a stronger attractive force among particles than gases, causing them to be closer together. Compared to solids, liquids have weaker attractive forces.

Dipole-dipole Forces vs. Hydrogen Bonding

• Dipole-Dipole Forces: A force that occurs between polar molecules, where the positive end of one molecule is close to the negative end of another. This interaction depends on the molecular shape and includes nonpolar substances that can be condensed into liquid or solid.
• Hydrogen Bonding: A stronger dipole-dipole force that involves an attraction between a hydrogen atom bonded to a highly electronegative atom (F, O, or N) and an unshared electron pair on another electronegative atom.

Intermolecular Forces and Viscosity

• Intermolecular Forces and Viscosity: The stronger the intermolecular forces, the more viscous the liquid. The smaller the molecules, the less viscous the liquid. The higher the temperature, the lower the viscosity. A liquid with stronger intermolecular forces will form smaller, spherical droplets on a surface whereas weaker intermolecular forces cause the liquid to spread out more. Furthermore a liquid with stronger intermolecular forces will have a higher boiling point and evaporate slower than a liquid with weaker forces.

Properties of Water

• Water's Properties: Water's high boiling point, resulting from strong hydrogen bonding, is the main reason it remains liquid at room temperature. The density of liquid water is greater than the density of solid water (ice).

Phase Transitions of Water and Carbon Dioxide

• Phase Transition Interpretation: When pressure increases, water (which is a liquid at room temperature) has a phase transition when pressure increases. Water transitions from a gaseous state to a solid state, when pressure increases. Carbon dioxide (which is in a solid state at 80 C) transitions to a gaseous state, only when pressure increases.

Cooling Curve of a Substance

• Cooling Curve: Liquids can be cooled below normal freezing points before freezing. The freezing point remains constant during a phase change.

Solution and Mole Fraction

• Mole Fraction: Given the mass of solute (NaOH) in g and mass of water in g, and the volume of the solution in mL, determine the mole fraction for NaOH.

Percent by Mass

• Calculate Percent by Mass: To find percent by mass, use the mass of the solute divided by the total mass of the solution (solute plus solvent), then multiply by 100.

Freezing Point

• Freezing Points: The freezing point of a solution is affected by the solute added within it.

Osmotic Pressure and Molar Mass

• Osmotic Pressure: Osmotic pressure depends on the molar mass of the sample. When the molar mass is calculated, ensure that significant figures are used in the final answer.

Homogeneous vs Heterogeneous Catalysts

• Homogeneous vs Heterogeneous Catalysts: Homogeneous catalysts interact uniformly with reactants, compared to heterogeneous catalysts' targeted interaction with reactants
• Catalyst Role: Catalysts provide an alternative reaction pathway with lower activation energy, thus increasing the rate of a reaction.

Zero-Order vs First-Order Reactions

• Zero-Order vs First-Order Reactions: Zero-Order reactions do not depend on the concentration of the reactants whereas First-Order reactions depend on the concentration of one reactant.

Test your understanding of intermolecular forces in liquids, solids, and gases with this quiz. Explore concepts like dipole-dipole forces, hydrogen bonding, and their effects on viscosity. Suitable for students in the second semester of General Chemistry.