Fill in the blank.
1) In a one component system with two phases (a gas and a liquid) the temperature at which the interface between the gas and the liquid disappears is called the __Answer__.
2) The point in the phase diagram at which the solid, liquid and
vapour phases of a one component system coexist is called the
__Answer__.
3) A solution that obeys Raoult’s law at all compositions
is called __Answer__.
4) A reaction for which the reaction free energy is greater than
zero is called __Answer___.
Multiple choice
5) If salt is added to pure water, the freezing point will
a) increase b) decrease c) stay the same d) can’t tell
6) If salt is added to pure water, the chemical potential of water
in the solution will
a) increase b) decrease c) stay the same d) can’t tell
7) The Gibbs energy of mixing two ideal solutions is
a) positive b) negative c) zero
8) A positive reaction free energy implies that a reaction is
spontaneous
a) True b) False c) can’t tell
9) A negative reaction enthalpy implies that a reaction is spontaneous
a) True b) False c) can’t tell
10) If a reaction has an equilibrium constant of 1.0, then the
standard reaction free energy is
a) positive b) negative c) zero
11) If a reaction has a standard reaction enthalpy that is positive,
then as temperature is increased, the equilibrium constant will
a) Increase b) Decrease c) stay the same d) can’t tell
12) What is the ratio of the concentration of the base form of
a weak acid to the concentration of the acid form when the pH
of the solution is 8.0 and the pKA of the weak acid is 7.0?
13) The pH of a 0.00001 mole/kg aqueous solution of NaOH is
14) In the reaction Cu2+ (aq) + Zn(s) <==> Cu(s) +Zn2+(aq),
a) Cu2+ is oxidized and Zn(s) is reduced
b) Cu2+ is reduced and Zn(s) is oxidized
c) both Cu2+ and Zn(s) are reduced
d) both Cu2+ and Zn(s) are oxidized.
15) The redox reaction in the last problem is spontaneous. This
means that the standard potential for an electrochemical cell
which utilizes this reaction must be
a) positive b) negative c) zero.
16) The units of a first order rate constant are
a) M (=moles/L) b) M/s c) 1/s d) 1/(Ms)
17) The units of a second order rate constant are
Numerical Problems
18) Consider the cell Zn | ZnSO4(aq) || AgNO3(aq) | Ag. a) What is the cell reaction for this cell? (Note that ZnSO4 dissociates in solution to form Zn(2+) and SO4(2-) and that AgNO3 dissociates to form Ag(+) and NO3(-)) b) Given table 10.5 in your book, what is the standard potential of this cell? c) What is the standard reaction Gibbs energy for the cell reaction in kJ/mol? d) What is the equilibrium constant for the cell reaction?
19) The rate of formation of C in the reaction A <==> 2B
+ 3C is 0.02 moles per liter per second when [A] = 0.3 mole/liter
and the concentrations of B and C are both zero. a) What is the
rate of decay of A and what is the rate of formation of B under
the same conditions? b) if the first order rate constant for the
reaction is 0.0222 per second, what will be the concentrations
of A, B and C after 1 second has past assuming the initial reaction
conditions were as stated above?
20) In the reversible reaction A + B <==> C, the forward
rate constant for formation of C from A and B is 3.0 per molar
per second and the reverse rate constant for formation A and B
from C is 6.0 per second. What is the a) equilibrium constant
and b) standard reaction Gibbs energy for this reaction? (Make
sure to include any units in your answers.)
Problems on most recent material
21) Explain the difference between electronic, vibrational, rotational and translational transitions? Which are the highest energy transitions?
22) What is the difference between the energy of an electronic orbital and the energy of a transition?
23) If I could build a perfect spectrophotometer, would I be able to resolve the vibrational lines that are on top of large molecule electronic spectra and are in part responsible for their width (in other words, could the inability to see vibrational bands in most large molecule spectra be overcome by increasing the wavelength resolution on my spectrophotometer)?
24) Holes burned into absorbance spectra at low temperature still have a width to them. If all of the nuclear motion (other than photo-induced changes in vibrational states) is essentially absent at this temperature, what determines the width of the holes?
25) What is the energy of a 500 nm photon in joules? in wavenumbers?
26) In theory (assuming 100% efficiency and standard conditions), how many 700 nm photons does a chloroplast have to absorb in order to make one ATP molecule from ADP and inorganic phosphate (The standard free energy change for the reaction ADP + Phosphate <==> ATP is about 30 kcals per mole)?
27) Many spectra become more narrow at low temperature. Suggest a reason why.
28) If the observed lifetime of an excited state is 1.0 (nanosecond)-1 and the natural radiative rate constant is 0.1 (nanoseconds)-1, what is the nonradiative decay rate constant?
29) The quantum yield of fluorescence from the photosynthetic reaction center of purple nonsulfur bacteria is about 10-4. The natural radiative decay rate is about 108 s-1. Assuming that photosynthetic electron transfer is the only nonradiative process which occurs, what is the rate constant for the initial electron transfer reaction in which the energy of the excited state of the reaction center is used to drive the transfer of an electron to a neighboring molecule?