Chapter 7 Flashcards
what is the first law of thermodynamics?
the total energy of the universe is constant. Energy cannot be created or destroyed. Or the conservation of energy.
non-spontaneous vs spontaneous?
non spontaneous processes require input to go. Spontaneous is on that occurs without on going outside intervention.
thermodynamics?
study of spontaneity of a reaction
a non spontaenous reaction is not ————-
impossible
the 2 thermodynamic functions that determine the chemical potential of a system are …..
enthalpy and entropy
enthalpy:
is a comparison of the bond energies of reactants to products in a chemical reaction
so although most spontaneous reactions are exothermic, some spontaenous reactions are endothermic, what are some examples?
- melting of ice above 0
- vaporation of liquid water to haseous water
- the dissolution of NaCl in water
what is noticeable about the spontaenous reactions discussed in the previous cue cards….
- melting of ice above 0
- vaporation of liquid water to haseous water
- the dissolution of NaCl in water
disorder or randomness increases
if W increases in thr equation S= k ln W what increases?
entropy
a system has greater entropy when….
- ) it has more energetically equivalent ways to arrange the components of the system
- ) the state with the highest entropy also has the greatest dispersal of energy
- ) a state in which a given amount of energy is more highly dispersed has more entropy than a state in which the same energy is more highly concentrated
second law of thermodynamics:
for any spontaneous process, the entropy of the universe increases.
processes that decrease the entropy of the universe do not occur ————
spontaneously
are enthalpy and entropy state functions?
yes
S final:
entropy of state in which atoms are distributed between both flasks
S initial:
entropy of state in which atoms are all in one flask
the entropy of a sample of matter ——- as it changes state from a solid to a liquid or from a liquid to a gas.
increases
if triangle Ssystem is negative then what is triangle Ssurroundings?
positive
the freezing of water become nonspontaneous above 0 because….
the magnitude of the increase in the entropy of the surroundings due to the dispersal of energy into the surroundings is temperature dependent
a process that emits heat into the surroundings (qsys negative) increases the entropy of the surroundings and results in what sign for triangle Ssurr?
poistive.
a process that absorbs heat from the surroundings (qsys positive) decreases the entropy of the surroundings therefore resulting in what sign for triangle Ssurr
negative
standard state for a gas:
pure gas at a pressure of exactly 1atm
standard state for a liquid or solid?
at a pressure of 1 atm and at the temp of interest often 25 degrees C
standard state for a substance in a solution?
concentration of exactly 1 M
the absolute zero of entriopy is given by the third law of thermodynamics which states:
the entropy of a perfect crystal at absolute zero (0K) is zero. Therefore the absolute entropy of substances is always +
the larger the molar masses the ——– the entropy
larger
Factors that affect standard molar entropy:
- the particular state of the substance g>l>s
2, a particular allotrope of the substance - molar mass of the substance
- molecular complexity of the substance
- extent or degree of dissolution
when K<1
reaction is spontaneous in the revser direction
whn K>1
reaction is spontaneous in forward dirction
when K=1,
the reaction happens to be at equilibrium under standard conditions
