Topic 5 states of matter and Energetics Flashcards
(23 cards)
What is a gas?
Widely spaced particles that completely fill the container
Define ideal gas.
A gas for which the relationship pV = nRT holds true
What characterizes a liquid?
Has fixed volume and takes up shape of container
What does the Maxwell-Boltzmann distribution illustrate?
Graph showing the distribution of kinetic energies among molecules
What is the molar volume of a gas at 273 K and 1 atm?
22.4 dm3
What defines a solid?
Has fixed shape and fixed volume
What is bond enthalpy?
The average enthalpy change of breaking a bond between gaseous atoms into its constituent gaseous atoms
What is the Born-Haber cycle?
Energy cycles for the formation of ionic compounds
What does Hess’s law state?
Enthalpy change for a reaction depends only on difference between enthalpy of products and enthalpy of reactants
What is calorimetry?
A device for measuring enthalpy changes for reactions
Define electron affinity.
Enthalpy change when an e- is added to an isolated atom in the gaseous state
What is an endothermic reaction?
A reaction in which energy is absorbed
What is enthalpy?
The internal energy stored in the reactants
What is entropy?
A measure of the disorder of a system
What causes entropy to increase? (list at least two)
- Increase of number of moles of gaseous molecules
- Change of state from solid to liquid or liquid to gas
Define exothermic reaction.
A reaction in which energy is evolved
What is Gibb’s free energy?
Must be – for reaction to be spontaneous
What does heat measure?
The total energy in a given amount of substance
What is lattice enthalpy?
The process of converting one mole of a crystalline solid into its gaseous ions
What is a spontaneous reaction?
A reaction that has a natural tendency to occur
What are standard conditions?
298 K and 1 atm
What does temperature measure?
The average kinetic energy
Fill in the blank: The lattice enthalpy increases with decreasing size of the ions and increasing _______.
charge
