Thermodynamics Flashcards
Diff between closed and isolated system
closed system: the external environment cannot contribute matter to the system but can contribute energy isolated: the external environment cannot contribute matter or energy to the system
what are the state variiables
fundamental property: includes pressure, volume, moles, entropy
Equation that represents the first law of thermodynamics
ΔEsystem=Q-W
Q is heat transferred (different from temp)
W positive when it is done by the system negative when work is done on the system
Q positive when heat entering system and negative when leaving system
T/F: Einternal is propotional to heat
True
isobaric process is ?
An isobaric process is a thermodynamic process in which the pressure remains constant. An isobaric expansion of a gas requires heat transfer to keep the pressure constant.
image of PV diagram: area under curve is work done
an isochoric process
thermodynamic process during which the volume remains constant, so pressure increases and the change in energy is equal to the heat, Q)
no work is done because there is no movement of the piston (equation W=PΔV does not apply here)
image is a PV diagram: area under curve is work done, *so since there’s no area, no work done*
an isothermal process is
temperature is constant.. this is because heat is allowed to pass freely between a sustem and its environment, maintaining an equilibrium in the system
because there’s an area under the curve, work must be done, therefore W= Q (heat transferred) and ΔE=O (because ΔE∝T)
an adiabatic process occurs when
no heat is transferred between the system and the environment and so the only energy transferred is work
*Some chemical and physical processes occur so rapidly that they may be conveniently described by the term “adiabatic approximation”
oxidation state rules
standard state refers to
The standard state of a chemical substance is its phase (solid, liquid, gas) at 25.0 °C and one atmosphere pressure. This temperature/pressure combo is often called “room conditions.”
Two elements are liquid in their standard state what are they?
mercury and bromine
State the standard state of each group:
- Metals *except Hg
- Metalloids
- Diatomics H2, N2, O2
- Diatomic halogens Fl2, Cl2, Br2, I2 (name each separately)
- Non-halogen Nonmetals: C, S, P etc
- solid
- solid
- All gases
- Fl2 gas, Cl2 gas, Br2 liquid, I2 solid
- solid
what is the relationship (direct or inverse) between reduction potential, the ability of a reactant to be oxidized or reduced, and the ability of the reactant to be a reducing or oxidizing agent
↑Reduction potential (Eo) in Volts ↑reducability of reactant ↑oxidizing agent
“The more positive the reduction potential, the easier it is to reduce the reactant, which makes it a stronger oxidizing agent.”
^all of these are with respect to the reactant which is by definition the thing that’s reduced
when determining which molecule from a set of options is the best reducing?/oxidizing? agent, you are looking at the agent on the reactant side of the equation
oxidizing
the cathode is _______ in a galvanic cell and _______ in an electrlytic cell
insert positive/negative
the cathode is positive in a galvanic cell and negative in an electrolytic cell
what is a concentration cell
a glavanic cell that has identical electrodes (both the same ion) but which has half cells with different ion concentrations. Standard voltage is zero but the actual voltage is not zero (per the nernst equation) so electrons will flow from the half-cell with the lower concentration (fewer positive ions; anode) to the half-cell with the higher concentration (more positive ions attract more electrons; cathode). When the concentrations of the solutions become equal, the reaction will stop
