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Lecture questions exam 1

Terms in this set (74)

What is the first law of thermodynamics for both he universe as a whole and a system?
energy can not be created nor destroyed, it can only be changed from one form to another. dE=0
Black holes are a game changer.
How do we define the change in the internal energy of a system?
It is equal to heat flow into or out of the system - the work done on or by the system (dE=q-w)
How do you calculate the flow of heat into or out of the system?
q= number of moles heat capacity change in temperature
How do you calculate the mechanical (PV) work (w) done on or by a system?
w= Pressure * change in Volume
Define enthalpy (H) mathematically?
H = PV + E
PV is mechanical work
E is energy
What is the enthalpy of formation?
The constant-pressure heat required to forma a chemical compound from the elements ( in their most stable form) at standard conditions.
What is the enthalpy of formation of an element in its most stable form under standard condition?
0
What is the enthalpy of reaction?
the quantity of energy transferred as heat during a chemical reaction
How do we use enthalpy's of formation to calculate enthalpy changes of reactions?
dHrxn = sum of products' enthalpies - sum of reactants' enthalpies
How is dS defined and calculated?
The change in "randomness" of the reaction
dS = q/T
What is the second law of thermodynamics?
dS universe > 0 for any process. The universe is always increasing in randomness
Define dG and explain how it can be used to determine whether a reaction will occur spontaneously?
It is the change in free energy of a system.
dG = dH - T*dS
dG < 0 means the system reacts spontaneously
dG > 0 means the system doesn't react spontaneously
What is the Gibbs free energy of formation for a compound (dGf^o) and how can it be used to calculate the Gibbs free energy of a reaction?
analogous to the enthalpy of formation.
- the change in free energy when a compound is formed from its elements in their most stable form under a standard set of conditions
dGrxn= sum of dG products - sum of dG reactants
What is the rate of change of G with respect to T (dG/dT) equal to?
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What is the rate of change of G with respect to P (dG/dP) equal to?
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Assuming that dSrxn is approximately constant, how do we estimate the value of dGrxn at different temperatures?
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Assuming that dVrxn is approximately constant, how do we estimate the value of dGrxn at different pressures?
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Define thermodynamic equilibrium
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How do we use G to predict when a mixture of reactants and products are at equilibrium?
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Define chemical potential mathematically and verbally
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What can we say about chemical potentials of the same component in two different phases at equilibrium?
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Define an ideal solution
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How do you use chemical potentials to calculate the Gibbs free energy change (dGrxn) of a reaction?
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What is the expression that gives the chemical potential of a component of an ideal solution?
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How do you write the equilibrium constant (K) in terms concentration of those components in a solution?
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What is the relationship between the equilibrium constant for a reaction and dG^o for that reaction?
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What are the typical standard state compositions for a solute, solvent, and a solid?
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Give the equation for the chemical potential of a component in a non ideal solution
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What is the relationship between the activity of a component and it's concentration (include definition of activity coefficient)?
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Write the equilibrium constant relationship in terms of activities
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In what sense is thermodynamic "effective" composition?
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What is fugacity?
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What are some sources of non-ideality for ions in aqueous solutions?
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How do we calculate ionic strength?
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How do we use the Debye-Hückel model to calculate activity coefficients?
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What are the limitations of the Debye-Hückel model?
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How do we use the Truesdell-Jones model to calculate activity coefficients?
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What limitations do the Truesdell-Jones model?
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What models do we use to calculate activity coefficients at very high ionic strengths?
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How do we use debye-huckel model to calculate activity coefficients
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What are the limitations of the debey-Huckel model
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How do we use the truesdell-jones model to calculate activity coefficients
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What are the limitations of the truesdell-jones model
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What models do we use to calculate activity at very high ionic strengths
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how do the activity coefficients of uncharged species vary with ionic strength
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what is the ion activity product and how can it be used to determine whether a solution is saturated, under saturated or over saturated with respect to a mineral
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define pH
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Define a neutral, acidic, and basic solution and explain how and why the boundaries between these vary with temperature
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what is an acid
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what is pKa
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what is a monoprotic acid, a diprotic acid, and a triprotic acid
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given pH how would you calculate the ratios of the dissociation products of acids (for example aHCO3/aH2CO3 and aCO3/aHCO3)
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What is a strong acid and what is the most important strong acid in natural systems?
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What is a weak acid and what are the most important weak acids in natural systems?
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What is silicic acid and how is it formed in natural systems
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what is a base?
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What is pKb
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how (in detail) can you calculate the pH of rainwater in equilibrium with a given concentration of CO2 in the atmosphere
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why, although most rain water is mildly acidic, is most surface water mildly basic?
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What are the equations and procedures are used to calculate the pH in equillibrium with the atmosphere and dolomite
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when calculating the pH of natural waters what is the difference between open and closed system?
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what does acidity measure
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what is Ca quantitatively
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What does alkalinity measure
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What is Cb quantitatively
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How do you express Ca or Cb in milli-equivalent per liter (meq/L)
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How are alkalinity and acidity determined empirically
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What is buffering?
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What is henderson-hasselbach equation and what is it used for
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what is the buffering index
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Be able to indentify and use the buffering index equations for monoprotic and diprotic acids
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what does Eh measure
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Explain how oxidation-reduction reactions can be used to make a batery and be able to use basic thermodynamic data to calculate the emf of that battery
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Use the nernst equation to calculate E
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