General Chemistry - Intermolecular Forces and Thermodynamics

These flashcards cover key concepts from the General Chemistry lecture notes on Intermolecular Forces and Thermodynamics, including properties of substances, reaction rates, and heat exchange.

What are Intermolecular Forces (IMF)?

Weak attractions between molecules that affect boiling point, melting point, and solubility.

What happens to boiling and melting points with stronger IMF?

Higher boiling and melting points.

What are London Dispersion Forces (LDF)?

The weakest IMF, caused by temporary electron movement, present in all molecules, dominant in nonpolar molecules.

What are Dipole-Dipole Forces?

Attractions between polar molecules where the partial positive end attracts the partial negative end.

What defines Hydrogen Bonding?

A special type of dipole-dipole force occurring when H is bonded to N, O, or F.

What explains water's high boiling point?

Hydrogen bonding contributes to its high boiling point.

What is the trend for LDFs in relation to molecular size?

Bigger molecules result in stronger London Dispersion Forces.

What is Surface Tension?

The energy needed to stretch the surface of a liquid, higher in liquids with strong IMF like water.

What causes Capillary Action?

The movement of liquid due to the attraction between liquid molecules and solid surfaces.

What is the effect of stronger IMF on viscosity?

Stronger IMF results in higher viscosity (thicker liquids).

What is Vapor Pressure?

The pressure exerted by gas molecules that escape from a liquid.

How does vapor pressure relate to IMF strength?

Weak IMF allows molecules to escape easily, resulting in high vapor pressure, while strong IMF leads to low vapor pressure.

What is the Molar Heat of Vaporization (ΔHvap)?

The energy needed to change 1 mole of liquid into gas.

What is the relationship between ΔHvap and boiling point?

Stronger IMF corresponds to higher ΔHvap and higher boiling point.

What describes the molecular structure of water?

Water (H₂O) is made of 1 oxygen atom and 2 hydrogen atoms, connected by covalent bonds.

What contributes to water's high specific heat?

Hydrogen bonds require a lot of heat to break, helping maintain stable temperatures.

What is the difference between crystalline and amorphous solids?

Crystalline solids have a long-range repeating structure, while amorphous solids lack a well-defined shape.

What are Ionic Crystals characterized by?

Composed of positive and negative ions, held by strong electrostatic forces, resulting in hard, brittle materials.

What defines Metallic Crystals?

Metal cations surrounded by a sea of delocalized electrons, characterized by malleability and conductivity.

How do Molecular Crystals function?

Composed of molecules held together by weak intermolecular forces.

What is Raoult’s Law?

It describes the vapor pressure of a solution based on the mole fraction of solvent and the vapor pressure of the pure solvent.

What is the purpose of specific heat?

It quantifies the amount of heat required to raise the temperature of a substance.

What are the basic principles of the First Law of Thermodynamics?

Energy cannot be created or destroyed, only converted; energy loss by the system equals the energy gained by the surroundings.

Define endothermic and exothermic reactions.

Endothermic reactions absorb heat from the surroundings while exothermic reactions release heat.

What is Hess's Law?

The total enthalpy change for a reaction is the same regardless of the number of steps taken.

What factor primarily affects reaction rates?

Concentration, temperature, particle size, nature of reactants, catalysts, and pressure for gases.

What is a catalyst?

A substance that increases the reaction rate by lowering the activation energy.

Define colligative properties.

Properties that depend on the number of solute particles in a solution rather than their identity.