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    Chemistry Calculations and Concepts

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    Determination of the Molar Mass and Ionization Constant of a Weak Monoprotic Acid

    Acetic Acid + Water yields Conjugate Base + Hydronium Ion Or HA + H20; H30+ + A-
    Calculation of the ionization constant for acetic acid from the measured pH of acetic acid samples:

    Acetic Acid titrated with Sodium Hydroxide and the following was determined or known before experiment:

    Avg. molar concentration of acetic acid titrated = 0.0455 mol/L
    Avg. pH = 3.19
    Standardized NaOH = 0.097 mol/L
    Mass concentration of acetic acid = 2.4 g/L

    Concentration and Ka calculations:
    1. Calculation of [H30+] = 10-3.19 = 6.46 X 10-4 ?? - (Is this the way to find the hydronium concentration?)
    2. Calculation of [A-] =
    3. Calculation of [HA] =
    4. Calculation of Ka = [H30+] [A-] =
    ___________

    [HA]

    Measurement of the pKa of Acetic Acid by the Half-Neutralization Method

    Using half the amount of NaOH required for equilibrium from part 1, the average pH vale was determined to be 4.63

    1. Calculation of pKa =
    2. Calculation of Ka =
    3. Calculation of [H30+] =
    4. Calculation of [A-] =
    5. Calculation of [HA] =

    Molar Mass and Ionization Constant of an Unknown Weak Monoprotic Acid

    Unknown acid = 1.84 g/L
    NaOH Titrant = 0.097 mol/L
    Average pH = 2.60
    Avg. molar mass = 0.04252 mol/L

    1. Calculation of pKa =
    2. Calculation of Ka =
    3. Calculation of [H30+] =
    4. Calculation of [A-] =
    5. Calculation of [HA] =

    Problem: OH- concentration of 0.050 M ammonia is 9.5 X 10-4

    (a) Write the chemical equation for the dissociation of NH3 in H2O

    NH3 + H2O; NH4 + OH-

    (b) Equilibrium constant expression for reaction of ammonia with water

    Kb = [OH-] [NH4+]
    ___________

    [NH3]

    (c) Calculate Kb using the above information

    © BrainMass Inc. brainmass.com April 3, 2020, 3:05 pm ad1c9bdddf
    https://brainmass.com/chemistry/chemical-equilibrium/chemistry-calculations-and-concepts-56986

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    This solution demonstrates how to calculate many chemistry problems such as concentrations and writing chemical equations.

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