chem2 Flashcards
(48 cards)
What distinguishes spontaneous processes from nonspontaneous processes?
Spontaneous processes occur naturally without external intervention, while nonspontaneous processes require energy input to occur.
What accompanies certain spontaneous processes in terms of matter and energy?
The dispersal of matter and energy.
Define entropy.
Entropy is a measure of the disorder or randomness of a system.
What is the relationship between entropy and the number of microstates?
Entropy increases with the number of microstates available to a system.
Predict the sign of the entropy change for a phase transition from solid to liquid.
Positive.
What are the second and third laws of thermodynamics?
The second law states that the total entropy of an isolated system can never decrease; the third law states that as temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.
How do you calculate entropy changes for phase transitions?
Using the formula ΔS = q_rev/T, where q_rev is the heat absorbed or released and T is the temperature in Kelvin.
Define Gibb’s free energy.
Gibb’s free energy is a thermodynamic potential that measures the maximum reversible work that can be performed by a system at constant temperature and pressure.
How is Gibb’s free energy related to spontaneity?
A process is spontaneous if the change in Gibb’s free energy is negative (ΔG < 0).
Calculate the free energy change using free energies of formation and entropies.
ΔG = ΣGf(products) - ΣGf(reactants) - TΔS.
What are microstates?
Microstates are specific configurations of a system that correspond to a particular macroscopic state.
How do changes in thermodynamic variables affect the entropy of a system?
Changes in temperature, volume, or pressure can increase or decrease the entropy of a system.
How do changes in thermodynamic variables affect the entropy of the surroundings?
Changes can lead to heat exchange, which affects the entropy of the surroundings and the universe.
What factors can predict the spontaneity of a system?
Enthalpic and entropic considerations.
Identify the three main states of matter.
Solid, liquid, gas.
What relationships exist among gas temperature, pressure, amount, and volume in ideal gases?
Described by the ideal gas law: PV = nRT.
What types of intermolecular forces exist in condensed phases?
- Dispersion forces * Dipole-dipole attractions * Hydrogen bonding.
How do intermolecular forces affect changes in state?
Stronger intermolecular forces result in higher temperatures needed for phase transitions.
What defines crystalline solids?
Crystalline solids have a well-ordered structure and distinct melting points.
List the main types of crystalline solids.
- Ionic solids * Metallic solids * Covalent network solids * Molecular solids.
Define phase transitions.
Phase transitions are changes from one state of matter to another.
What is the relationship between phase transition temperatures and intermolecular forces?
Higher intermolecular forces typically lead to higher phase transition temperatures.
What do heating and cooling curves represent?
They show the relationship between temperature and heat flow during phase changes.
What is molarity?
Molarity is the number of moles of solute per liter of solution.
