Entropy
Which of the following has the highest standard molar entropy, S, at 25C
B. Cl2 (g)
C. F2 (g)
D. N2 (g)
Consider a reaction that has a positive H and a positive S. What statement is true?
A.) this reaction will be nonspon. at all temps.
B.) this reaction will be spon. at all temps
C.) this reaction will be spon. only at low temps.
D.) this reaction will be nonspon only at low temps.
D.) this reaction will be nonspon only at low temps.
What sign (-) or (+) represents a spontaneous reaction.
(-) = spontaneous
Calculate Srxn under standard conditions.
4NH3 + 5O2 -> 4NO + 6H2O
192.8 205.2 210.8 188.8
178.8 J/K
What element is being oxidized in the following redox reaction?
MnO4- + H2C2O4 -> Mn2+ (aq) + CO2 (g)
C
What are the two factors that affect entropy, S
- Change in temperature
- Change in state
Consider a reaction that has a negative H and positive S. Which statement is true.
A.) this reaction will be spon. at all temps.
B.) this reaction will be spon. only at high temps.
C.) this reaction will be nonspon. at all temps.
D.) this reaction will be nonspon only at high temps.
A.) this reaction will be spon. at all temps.
Above what temperature does the following reaction become nonspontaneous?
FeO (s) + CO (g) -> CO2 (g) + Fe (s)
H= -11.0kJ S= -17.4J/k
632K
Estimate Grxn, at 449K.
CH2O + 2H2 -> CH4 + H2O
H= -94.9 KJ ; S= -224.2 J/K
(express answer in kJ)
5.8 kJ
Balance the following redox reactions in acidic solution. What are the coefficients in front of Zn and H+?
Zn2+ (aq) + NH4+ (aq) -> Zn (s) + NO3- (aq)
Zn - 4
H+ - 10
Which of the following processes have a S>O
A.) Na2CO3 (s) + H2O (g) -> CO2 (g) + 2NaHCO3
B.) CH2OH (l) -> CH3OH (s)
C.) N2 (g) + 3H2 (g) -> 2NH3 (g)
D.) CH4 (g) + H2O (g) -> CO (g) + 3H2 (g)
A.) this reaction will be nonspon. at all temps.
B.) this reaction will be spon. only at low temps.
C.) this reaction will be spon. at all temps.
D.) this reaction will be nonspon. only at low temps.
B.) this reaction will be spon. only at low temps.
Below what temperature does the following reaction become nonspontaneous?
2HNO3 (aq) + NO (aq) -> 3NO2 (g) + H2O (l)
H = 136.5kJ; S = 287.5 J/K
475K
Use Hess' law to calculate Grxn using the following information.
ClO + O3 -> Cl + 2O2 Grxn = ?
2O3 + 3O2 Grxn = 489.6 kJ
Cl + O3 -> ClO + O2 Grxn = -34.5 kJ
524.1 kJ
Determine the cell notation for the redox reaction given below
Pb (s) + 2H+ (aq) -> Pb2+ (aq) + H2 (g)
Pb(s) | Pb2+(aq) || H+ (aq) | H2 (g) | Pt
Which of the following processes have a S<O?
A.) isopropyl alcohol condenses
B.) methanol (g at 555K) --> methanol (g, at 400K)
C.) water freezes
D.) CO2 (g) -> CO2 (s)
E.) All of the above
Use the information to determine the value of Ssurr at 298K. Predict whether this reaction is spontaneous or not.
N2 (g) + 2O2 (g) -> 2NO2 (g)
Ssurr = -223 J/K, reaction is not spontaneous
About what temperature does the following reaction become nonspontaneous?
2H2S (g) + 3O2 (g) -> 2SO2 2H2O (g)
H= -1036kJ; S=-153.2J/K
6.762x10^3 K
Determine the equilibrium constant for the following reaction at 298K
SO3 + H2O -> H2SO4
G= -90.5 kJ
7.31x10^15
Given the following reaction, calculate Ssurrounding at 25C,
2N2 (g) + O2 (g) -> 2NO2 (g)
Hrxn = 183.2kJ
.614 kJ
Place the following in order of increasing standard molar entropy.
H2O (l), H2O (g), H2O (s)
H2O (s) < H2O (l) < H2O (g)
Calculate G, at nonstandard state at 298K for a mixture of 2.0atm NH3, 1.0atm O2, 1.5atm H2O, and 1.2atm NO.
4NH3 + 5O2 -> 6H2O +4NO
-9.5x10^5 J/mol
Determine the equilibrium constant for the following reaction at 298 K.
Cl(g) + O3(g) -> ClO(g) + O2(g)
G° = - 34.5 kJ
1.12x10^6