Questions and Answers
What intermolecular forces exist between molecules of ethanol?
What intermolecular forces exist between molecules of dimethyl ether?
What is osmosis?
The spontaneous migration of water through a semipermeable membrane from high concentration of water (low solute) to low concentration of water.
What is a semipermeable membrane?
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What describes a hypertonic solution?
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What is an isotonic solution?
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What characterizes a hypotonic solution?
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What is osmotic pressure?
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In the equation pi = MRT, what does M represent?
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What are colligative properties?
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What does the van't Hoff factor indicate?
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Match the following terms with their definitions:
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A pseudo-first-order reaction occurs when all the reactants but one are present at low concentrations.
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What is activation energy (Ea)?
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What is the Clausius-Clapeyron equation used for?
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What describes the transition state in a chemical reaction?
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What determines the reaction order?
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What is the rate constant?
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What does the rate law express?
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Study Notes
Intermolecular Forces
- Ethanol exhibits London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
- Dimethyl ether shows London dispersion forces and dipole-dipole interactions.
Osmosis and Membranes
- Osmosis involves water moving through a semipermeable membrane from high to low water concentration.
- A semipermeable membrane allows water to flow but restricts hydrated particles.
Tonicity of Solutions
- Hypertonic solutions have a higher solute concentration than red blood cells, leading to cell shrinkage.
- Isotonic solutions match solute concentrations in cells, resulting in no net osmotic flow.
- Hypotonic solutions have a lower solute concentration than cells, causing cells to expand.
Osmotic Pressure
- Osmotic pressure prevents water from moving across a membrane due to concentration differences.
- The formula for osmotic pressure is π = iMRT, where i is the van't Hoff factor, M is molarity, R is the gas constant, and T is the temperature.
Colligative Properties
- Colligative properties rely on particle concentration rather than the identity of the solute.
- Van't Hoff factors indicate actual particle count in solution versus theoretical counts if no dissociation occurs.
Desalination and Water Purification
- Desalination removes ions from seawater through methods like distillation and reverse osmosis.
Vapor Pressure and Volatility
- Vapor pressure reflects the extent to which a gas is in equilibrium with its liquid phase.
- Volatility is associated with higher vapor pressures; more volatile substances evaporate easily.
Thermodynamics and Energy
- Spontaneous processes occur without external intervention, while non-spontaneous processes require energy input.
- The second law of thermodynamics states total entropy in the universe increases with spontaneous reactions.
- Third law: Entropy of a perfect crystal is zero at absolute zero temperature.
Gibbs Free Energy
- Gibbs free energy measures work capability of thermodynamic systems; G = H - TS, where H is enthalpy, T is temperature, and S is entropy.
Photochemical Smog
- Formed from sunlight reacting with pollutants from combustion engines, combining gases and particles.
Chemical Kinetics
- Chemical kinetics studies reaction rates and concentration changes during reactions.
- Factors influencing reaction rates include concentration, temperature, and presence of catalysts.
Rate Laws and Reaction Orders
- Rate laws describe the relationship between concentration and reaction rate: rate = k[A]^m[B]^n, where k is the rate constant.
- Overall reaction order is the sum of exponents in the rate law.
Half-Life and Reaction Mechanics
- Half-life (t1/2) is the time for a reactant's concentration to decrease by half; inversely related to reaction rate.
- Pseudo-first-order reactions occur when one reactant is in excess concentration.
Activation Energy
- Activation energy (Ea) is the minimum energy required for molecules to react during collisions.
- Increasing temperature raises reaction rates.
Catalysts
- Catalysts are substances that increase reaction rates without being consumed, lowering activation energy.
- Homogeneous catalysts share a phase with reactants, whereas heterogeneous catalysts exist in a different phase.
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Test your knowledge with these flashcards for Chem 1040 Exam 1, focusing on intermolecular forces and key concepts like osmosis. Each card presents a question and its detailed answer, making it a great tool for exam preparation.