Consider the ionization of aqueous ammonia: NH3(aq) + H2O(l) ⇌
NH4 + (aq) + OH- (aq)
a)Using the thermodynamic data from the textbook (Appendix C),
calculate the values of ∆H°rxn, ∆G°rxn, and ∆S°rxn for this process
at 25o C.
b)Calculate the value of Kb (with 2 sig figs) at 25o C from the
value of ∆G°rxn.
c) The value of ∆G°rxn you obtain (if your calculations are
correct) must be positive, indicating that the reaction in question
is non-spontaneous. Why...
Dissociation Constant
For the dissociation reaction of a weak acid in water,
HA(aq)+H2O(l)?H3O+(aq)+A?(aq)
the equilibrium constant is the acid-dissociation
constant, Ka, and takes the form
Ka=[H3O+][A?][HA]
Weak bases accept a proton from water to give the conjugate acid
and OH? ions:
B(aq)+H2O(l)?BH+(aq)+OH?(aq)
The equilibrium constant Kb is called the
base-dissociation constant and can be found by the formula
Kb=[BH+][OH?][B]
When solving equilibrium-based expression, it is often helpful
to keep track of changing concentrations is through what is often
called an...
What is the equilibrium constant expression for the following
reaction:
HCN(aq) +
H2O(l)↔CN−(aq) +
H3O+(aq)
Choose from the list below and enter the letters alphabetical
order. (e.g. For an equilibrium constant of
[H3O+]-1eq[HCN]eq
enter AH.)
A) [HCN]eq
E) [HCN]-1eq
I)
[Ru(NH3)62+]6eq
B) [H2O]eq
F) [H2O]-1eq
J) [Ru2+]-6eq
C) [CN-]eq
G) [CN-]-1eq
K) [NH3]-6eq
D) [H3O+]eq
H) [H3O+]-1eq
L)
[Ru(NH3)62+]-6eq
What is the equilibrium constant expression for the following
reaction: C5H5NH(aq) + H2O(l)↔C5H5NH2+(aq)+OH−(aq) Choose from the
list below and enter the letters alphabetical order. (e.g. For an
equilibrium constant of [OH-]-1eq[H2O]eq enter AH.)
A) [H2O]eq
E) [H2O]-1eq
I) (XPbI2)2eq
B) [C5H5NH]eq
F)
[C5H5NH]-1eq
J) [Pb2+]-2eq
C)
[C5H5NH2+]eq
G)
[C5H5NH2+]-1eq
K) [I-]-2eq
D) [OH-]eq
H) [OH-]-1eq
L) (XPbI2)-2eq
1 Write a balanced equilibrium equation and equilibrium constant
expression for the dissolution of Ca(OH)2(s).
2. If a compound is only slightly soluble, will the equilibrium
lie “to the left” or “to the right” if the equation is written with
solid on the left and the ions on the right?
3. Will the equilibrium constant (Ksp) be large or small for the
reaction in question number 2?
Hydrocyanic acid will set up the following equilibrium when
dissolved in water:
HCN(aq) + H2O(l) <--> CN-(aq)
+H3O+(aq)
a) calculate the pH of a .123 M solution of hydrocyanic acid
ANSWER: pH = 5.01
b) To 500mL of the solution in part (a) is added 5.00g of solid
NaCN. Calculate the pH of new solution. Assume no volume change has
occured.
c) If one were to add 10.00mL of a .100M NaOH solution to the
solution prepared in part (b),...
For the reaction of dissolution of lithium sulfate in water the
equilibrium constant is positive (K > 1).
Li2SO4(s) ⇌ 2
Li+(aq) +
SO4-2(aq)
ΔrHo = -30.5 kJ/mol
Which of the following statements is correct?
A. You can dissolve a larger amount of lithium sulfate in hot
water than in cold water.
B. The entropy of the system increases when lithium sulfate
dissolves in water.
C. The reaction as written is not spontaneous at standard
conditions.
D. Dissolution of lithium...
Reaction 1: NH4+(aq) + H2O(l)NH3 + H3O+(aq) pKA = 9.2
the system described above, it has been found that the activity
coefficients for the species in solution are: (NH4+) = 0.80,
(H3O+) = 0.90, (OH-) = 0.88 – the activity coefficients for
neutral molecules are 1.0.
a.) Write down the equilibrium expression for Reaction 1 in
terms of activity coefficients and concentrations – i.e. the
correct equilibrium expression which is NOT just in terms of
concentrations.
b.) Now algebraically manipulate...
What salt is produced in each of the following neutralization
reactions?
HNO3(aq)+KOH(aq)→H2O(l)+?
HNO3(aq)+Ca(OH)2(aq)→H2O(l)+?
HCl(aq)+Ca(OH)2(aq)→H2O(l)+?
HCl(aq)+KOH(aq)→H2O(l)+?
Drag the appropriate items to their respective
reaction. K2NO3, KNO3, Ca(NO3)2, CaNO3, CaCl, CaCl2,
KCl2, KCl
Reaction A-
Reaction B-
Reaction C-
Reaction D –
Not a product -