Explore BrainMass

Explore BrainMass

    Aqueous Ionic Equilibrium 2

    Not what you're looking for? Search our solutions OR ask your own Custom question.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    Aqueous Ionic Equilibrium 2
    1- Which of the following processes will result in an increase of entropy of the system? Choose from:

    2- What does the standard change in Gibbs free energy ( ) of a reaction tell us about the equilibrium constant (K) for that reaction under standard conditions? Choose from:
    There is no significant relationship between and K.
    A negative indicates that product formation is favored, and K will be greater than 1.
    A negative indicates that reactant formation is favored, and K will be less than 1.
    3- Which of the following combinations of and describe a process that is only spontaneous at low temperatures? Choose from:
    : positive , : positive
    : negative , : positive
    : positive , : negative
    : negative , : negative
    Spontaneity is not related to the sign of and .

    4- AB 2 has a molar solubility of 3.72×10 −4 M . What is the value of the solubility product constant for AB2 ?
    5- C 2 D 3 has a solubility product constant of 9.14×10 −9 . What is the molar solubility of C 2 D 3 ?
    6- A buffer contains significant amounts of ammonia and ammonium chloride.
    Part A:Write an equation showing how this buffer neutralizes added acid (HI)
    Part B: Write an equation showing how this buffer neutralizes added base (CsOH). Express your answer as a chemical equation.
    7- Solve an equilibrium problem (using an ICE table) to calculate the pH of each solution:
    Part A: a solution that is 0.165M in HC 2 H 3 O 2 and 0.120M in KC 2 H 3 O 2
    Part B: a solution that is 0.185M in CH 3 NH 2 and 0.110M in CH 3 NH 3 Br
    8- A 1.0-L buffer solution is 0.105M in HNO 2 and 0.145M in NaNO 2 . Express your answers using three significant figures separated by a comma.
    Part A: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g HCl
    Part B: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g NaOH .
    Part C: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g HI.

    © BrainMass Inc. brainmass.com December 24, 2021, 11:16 pm ad1c9bdddf
    https://brainmass.com/chemistry/general-chemistry/aqueous-ionic-equilibrium-553571

    Attachments

    SOLUTION This solution is FREE courtesy of BrainMass!

    Aqueous Ionic Equilibrium 2
    1- Which of the following processes will result in an increase of entropy of the system? Choose from:

    Entropy will increase when moles of gas increases like when 2 moles of NH3 forms a total of 4 moles of gaseous products N2 and H2.

    2- What does the standard change in Gibbs free energy ( ) of a reaction tell us about the equilibrium constant (K) for that reaction under standard conditions? Choose from:
    There is no significant relationship between and K.
    A negative indicates that product formation is favored, and K will be greater than 1.
    A negative indicates that reactant formation is favored, and K will be less than 1.

    A reaction will be spontaneous when dG is negative. Hence product formation is favored and K must be greater than 1.
    3- Which of the following combinations of and describe a process that is only spontaneous at low temperatures? Choose from:
    : positive , : positive
    : negative , : positive
    : positive , : negative
    : negative , : negative
    Spontaneity is not related to the sign of and .

    dG = dH - TdS
    For spontaneity only at low T, dH must be negative and dS negative.
    4- AB 2 has a molar solubility of 3.72×10 −4 M . What is the value of the solubility product constant for AB2 ?

    AB2 -- A2+ + 2B-
    Ksp = (s)(2s)^2 = 4s^3
    Ksp =4 (3.72 x 10-4)3 = 2.06 x 10-10

    5- C 2 D 3 has a solubility product constant of 9.14×10 −9 . What is the molar solubility of C 2 D 3 ?

    C2D3 -- 2C3+ + 3D2-
    Ksp = (2s)2(3s)3 = 108s5
    9.14 x 10-9 = 108 s5
    Hence s= 0.00967 M

    6- A buffer contains significant amounts of ammonia and ammonium chloride.
    Part A:Write an equation showing how this buffer neutralizes added acid (HI)
    HI + NH3 -- NH4+
    Part B: Write an equation showing how this buffer neutralizes added base (CsOH). Express your answer as a chemical equation.
    NH4+ + Cl - + CsOH -- NH3 + Cs+ + Cl- + H2O
    7- Solve an equilibrium problem (using an ICE table) to calculate the pH of each solution:
    Part A: a solution that is 0.165M in HC 2 H 3 O 2 and 0.120M in KC 2 H 3 O 2
    C2H3O2 - + H2O -- HC2H3O2 + OH-
    Initial 0.165 0.120
    Change -x +x +x
    Eqbm 0.165-x 0.120+x x
    Kb = 5.56x10-10 = (0.120)(x) / 0.165 approximating 'x' to be really small
    Solving gives x = 7.64 x 10-10
    pOH = 9.12
    Hence pH = 4.88
    Part B: a solution that is 0.185M in CH 3 NH 2 and 0.110M in CH 3 NH 3 Br
    CH3NH3+ -- CH3NH2 + H+
    Initial 0.110 0.185
    Change -x +x +x
    Eqbm 0.110-x 0.185+x x
    Ka = 2..27x10-11 = (0.185)(x) / 0.110 approximating 'x' to be really small
    Solving gives x = 1.35x 10-11
    Hence pH = 10.87

    8- A 1.0-L buffer solution is 0.105M in HNO 2 and 0.145M in NaNO 2 . Express your answers using three significant figures separated by a comma.
    Part A: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g HCl
    1.4g HCl = 1.4/ 36.46 = 0.0384 mol
    HCl will react with NaNO2 to form HNO2 thus increasing HNO2 while decreasing NaNO2
    pH = pKa + log [NO2-]/[HNO2]
    pH = 3.40 + log[0.145 - 0.0384]/[0.105 + 0.0384]
    pH = 3.27
    Part B: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g NaOH .
    1.4g NaOH= 1.4/ 39.997 = 0.035mol
    NaOH will react with HNO2 to form NO2- thus increasing NO2- while decreasing HNO2
    pH = pKa + log [NO2-]/[HNO2]
    pH = 3.40 + log[0.145 + 0.035]/[0.105 - 0.035]
    pH = 3.81

    Part C: Determine the concentrations of HNO 2 and NaNO 2 after addition of 1.4g HI.
    1.4g HI= 1.4/ 127.91 = 0.0109mol
    Addition of HI will increase the HNO2 concentration and decrease NO2-
    pH = pKa + log [NO2-]/[HNO2]
    pH = 3.40 + log[0.145 - 0.0109]/[0.105 + 0.0109 ]
    pH = 3.46

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    © BrainMass Inc. brainmass.com December 24, 2021, 11:16 pm ad1c9bdddf>
    https://brainmass.com/chemistry/general-chemistry/aqueous-ionic-equilibrium-553571

    Attachments

    ADVERTISEMENT