Gen Chem II: Exam 1 Flashcards
study of energy and its transformations
thermodynamics
heat involved in chemical and physical transformations
thermochemistry
ability to do work
energy
Total energy of a system appears as — and —
heat and work
system can transfer heat and vapor= mass and energy exchange
open
system can transfer heat= energy exchange
closed
system has no transfer or exchange
isolated
only depend on the state of a system, they do not depend on the path taken
state functions
energy is a —
state function
heat and work are or aren’t state functions?
aren’t state functions
when energy is released into the surrounds, change E is —
negative
when E is absorbed from the surroundings, change E is —
positive
heat is released into the surroundings; give change E, Q, and exothermic or endothermic
change E is negative and q is negative and the reaction is exothermic
heat is absorbed from the surroundings; give change E, Q, and exothermic or endothermic
change E is positive and q is position and the reaction is endothermic
the transfer of thermal energy between two bodies that are at different temperatures
heat
measure of thermal energy
temperature
the amount of heat required to raise the temperature of the entire sample by 1 C
heat capacity C
the heat for mol to increase by 1 C
molar heat capacity C(molar)
the heat for1 gram to increase by 1 C
specific heat capacity s
what has the highest specific heat
water
the first law of thermodynamics
energy can be converted from one form to another, but cannot be created or destroyed
if w is positive, work is done — the system
on
if w is negative, work is done — the system
by
is enthalpy a state function?
yes
change in enthalpy and the change is — are approximately the same
E
used to quantify heat flow into or out of a system in a process that occurs at constant pressure.
enthalpy H
when heat is going out, change H is —. this is a — process
negative
exothermic
when heat is going in, change H is —. This is a — process
positive
endothermic
the change in enthalpy is the same whether the reaction takes place in one step or many steps
Hess’s Law
the enthalpy change that results when 1 mol of a compound is formed from its elements in their standard states
standard enthalpy of formation
the standard enthalpy of formation for any element in its standard state
0
the enthalpy of a reaction carried out at 1 atm
standard enthalpy of reaction
the device that measures heat transferred at constant pressure
calorimeter
why is there no work done in a bomb calorimeter
there is no change in volume
why can you not do work against a vacuum?
pressure is 0
calorimeter at constant volume
bomb calorimeter
doesn’t require a constant input of energy to occur
spontaneous reaction
reactions are spontaneous in — direction
one
can spontaneous reactions be either endothermic or exothermic?
both
result in an increase in the degrees of freedom of the particles in the system
spontaneous endothermic processes
measure of disorder
entropy S
the number of possible combinations of these types of motion and its related and it is related to the entropy of a system
microstates W
microstates increase with the number of —
particles
is entropy conserved?
no
the third law of thermodynamics
a perfect crystal has zero entropy at absolute zero
change S is — if the gas increases
positive
change S is — is the gas decreases
negative
change S is — if the product formed has more freedom
positive
for an exothermic reaction, change S is —
positive
for an endothermic reaction, change S is —
negative
H is always bigger or smaller than S?
bigger
gives the ratio of equilibrium concentrations of chemical species
the equilibrium constant K(c)
the ratio of product to reactant concentrations at any point in a reaction
the reaction quotient Q(c)
at equilibrium Q= –
K
indicates how close to the reaction is to equilibrium and in which direction it will spontaneously proceed to reach equilibrium
the value of Q
when Q is — than K, the reaction will proceed in the forward direction until Q=K. The [product] is too low and this is a spontaneous process.
less than
when Q is — than K, the reverse reaction is spontaneous. The [product] is too high. the reaction proceeds in the reverse reaction until Q=K
greater than
unitless thermodynamic equilibrium constant
activity K
what is the only thing that will ever change the value of K?
temperature
describe an exothermic process in terms of K
will always have a lower K at higher temperatures
describe an endothermic process in terms of K
will always have a higher K at higher temperatures
when the surroundings loose heat (exo or endo?)
endothermic
when the system gains heat (exo or endo?)
endothermic
when the surroundings gain heat (exo or endo)
exothermic
when the system looses heat (exo or endo)
exothermic
when a gas is compressed, the work is —
positive
surroundings on doing work on a system when a gas is —
being compressed
when the surroundings are doing work on the system, work is —
positive
when a gas is expanding, work is —
negative
when the system is doing work on the surroundings, work is —
negative
when the system is doing work on the surroundings, the gas is —
expanding
when is the only time you calculate energy using reactants minus products
bond energy
as entropy —, microstates —
increases
increase
at constant pressure, q equals —
change H
at constant volume, q equals —
change E
name 4 situations where work would be 0
when there is no change in volume (when there is no change in the number of moles of gas)
a vacuum: no pressure
when there are any states besides a gas
what is Q at standard states
1
standard states
1 atm
1 M
change V is a state function?
yes
Q can be a ratio of — or —
pressure or concentration
is Q a constant?
no
is K a constant?
yes
