Chem 1040 Exam 1 Flashcards

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Questions and Answers

What intermolecular forces exist between molecules of ethanol?

London dispersion forces

Dipole-dipole interactions

Hydrogen bonding

All of the above (correct)

What intermolecular forces exist between molecules of dimethyl ether?

London dispersion forces (correct)

Dipole-dipole interactions (correct)

Hydrogen bonding

None of the above

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?

Channels through which water flows but not hydrated particles. Signup and view all the answers

What describes a hypertonic solution?

A solution containing a higher concentration of solutes than inside a red blood cell. Signup and view all the answers

What is an isotonic solution?

A solution that matches the concentration of solutes in cells. Signup and view all the answers

What characterizes a hypotonic solution?

A solution that contains a lower concentration of solutes than inside a cell. Signup and view all the answers

What is osmotic pressure?

The pressure applied across a semipermeable membrane to stop the flow of water from a less concentrated to a more concentrated solution. Signup and view all the answers

In the equation pi = MRT, what does M represent?

The total molar concentration of all the solute particles. Signup and view all the answers

What are colligative properties?

Characteristics of solutions that depend upon the concentration and not the identity of the particles dissolved in the solvent. Signup and view all the answers

What does the van't Hoff factor indicate?

The ratio of the concentrations of solute particles in a solution to those that would exist if the solute did not dissociate. Signup and view all the answers

Match the following terms with their definitions:

Osmotic pressure = The pressure applied across a semipermeable membrane to stop water flow Chemical kinetics = The study of rates of change of concentration of substances Catalyst = A substance that increases the rate of a reaction without being consumed Entropy = A measure of how dispersed the energy in a system is Signup and view all the answers

A pseudo-first-order reaction occurs when all the reactants but one are present at low concentrations.

False Signup and view all the answers

What is activation energy (Ea)?

The minimum energy required for molecules to react when they collide. Signup and view all the answers

What is the Clausius-Clapeyron equation used for?

Relating the vapor pressure of a substance at different temperatures to its heat of vaporization. Signup and view all the answers

What describes the transition state in a chemical reaction?

A high-energy state between reactants and products. Signup and view all the answers

What determines the reaction order?

An experimentally determined number defining the dependence of the reaction rate on the concentration of a reactant. Signup and view all the answers

What is the rate constant?

The proportionality constant that relates the rate of a reaction to the concentration of reactants. Signup and view all the answers

What does the rate law express?

The experimentally determined relation between the concentration and rate of the reaction. Signup and view all the answers

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.