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40 Cards in this Set

  • Front
  • Back
What does the 1st law of thermodynamics (energy is conserved) NOT address about a reaction?
The extent to which it occurs
A process that occurs of its own accord without any ongoing outside intervention is said to be...
Spontaneous
T/F: Processes that are spontaneous in one direction are nonspontaneous in the opposite direction.
True
T/F: At the normal melting point of a substance, the solid and liquid phases are in equilibrium.
True
T/F: Thermodynamics can tell us the DIRECTION and EXTENT of a reaction but tells us nothing about the SPEED of the reaction.
True
T/F: An ideal engine with maximum efficiency operates under an ideal set of conditions in which all the processes are reversible.
True
In what type of process is a system changed in such a way that the system and surroundings can be restored to their original state by exactly reversing the change?
A reversible process
T/F: A reversible change produces that maximum amount of work that can be achieved by the system on the surroundings.
True
T/F: Reversible processes are those that reverse direction whenever an infinitesimal change is made in some property of the system.
True
A constant-temperature process is said to be...
Isothermal
In general, any irreversible process results in an overall increase in entropy, whereas a reversible process results in no overall change in entropy. What is this called?
The second law of thermodynamics
T/F: The total entropy of the universe increases in any spontaneous process.
True
The motion of a molecule in one singular direction is called...
Translational motion ("motional energy")
When the atoms in a molecule move periodically toward and away from one another, this motion is called...
Vibrational motion ("motional energy")
When a molecule is spinning, its motion is called...
Rotational motion
The particular set of positions and energies of the individual gas molecules in a random system is known as the _ of the thermodynamic system.
Microstate
T/F: Entropy is a measure of how many microstates are associated with a particular macroscopic state.
True
T/F: Entropy increases with the number of microstates of the system
True
T/F: The number of microstates available to a system increases with an increase in volume, an increase in temperature, or an increase in the number of molecules because any of these changes increases the possible positions and energies of the molecules of the system.
True
T/F: Although the solution process is normally accompanied by a net increase in entropy, the dissolving of salts with highly charged ions can result in a net DECREASE in entropy.
True
Name the 3 general situations in which the entropy of a system will increase.
From a solid to a gas, or from a solid to a liquid, and when the number of gas molecules increases during a chemical reaction.
What states that the entropy of a pure crystalline substance at absolute zero is zero?
The third law of thermodynamics
What happens to the entropy vs. state temperature graph as a substance transitions from a solid to a liquid, and then to a gas?
It undergoes a steady increase until the melting and boiling points, at which there is an abrupt increase in entropy because there are more microstates available.
What are the units for entropy?
J/mol-K
S° is known as the...
Standard molar entropy (1 atm pressure)
Why do standard molar entropies usually increase with increasing molar mass?
Because more molar mass usually means more atoms which leads to more possible microstates.
In the ΔS equation, what to the coefficients n and m stand for?
The coefficients in the chemical equation
T/F: Moles cancel out in the ΔS equation so that the units for ΔS are J/K, or Jelvins.
True
What might you have to do in order to find the ΔH required for the ΔS equation?
Find the ΔH(reaction), which is found by multiplying the ΔH of the products times the coefficient, and subtracting by the same thing of the reactants.
ΔS(universe) is always positive for any...
Spontaneous reaction
T/F: Spontaneous processes that result in a decrease in the system's entropy are always exothermic.
True
What is the Gibbs free energy equation relating enthalpy and entropy of a system?
ΔG = ΔH -TΔS
At constant temp and press, if ΔG is negative, the reaction is...
Spontaneous
At constant temp and press, if ΔG is zero the reaction is at...
Equilibrium
At constant temp and press, if ΔG is positive, the reaction is...
Nonspontaneous and requires work input from the surroundings
T/F: In any spontaneous process at constant temp and press, the free energy always decreases.
True
T/F: The free energies of elements in their standard states are set to zero.
True
T/F: You can ALSO calculate the standard ΔG by using the ΔG of formation.
True
What happens when T > 0°C?
The magnitude of -TΔS is greater than the magnitude of ΔH, so ΔG is negative and the process is spontaneous (must look at the equation to understand this)
What is the value of ΔG° at equilibrium?
0