Analytical Chemistry: Monoprotic Acid-Base Titration

Which indicator could be used to titrate aqueous NH3 with HCl solution?

• A

• B

• C

• D

• E

Which of the following statements about the equivalence point of an acid-base titration is true?

• The equivalence point of an acid-base titration is the same as the indicator endpoint.

• The equivalence point of an acid-base titration is the point where there is an equivalent amount of titrant and titrand.

• The equivalence point of an acid-base titration is where the pH = 7.0 (neutral).

• The equivalence point of an acid-base titration is where the entire volume of the buret has been used.

• The equivalence point of an acid-base titration is the average value of the dissociation constants.

There are two types of metal hydroxides, soluble metal hydroxides and insoluble hydroxides, both of which are strong bases. Which of the following statements is NOT true for strong bases?

• Dilute solutions are completely dissociated.

• For strong base solutions with a concentration between 10^-6 and 10^-8 M, the pOH is determined using systematic equilibrium.

• For strong base solutions with concentrations greater than or equal to 10^-6 M, the pOH is calculated from the concentration of the strong base.

• For strong base solutions with concentrations less than or equal to 10^-8 M, the pOH is always 7.

• Fe(OH)2 is a strong soluble base.

A(n) ___ is a compound with a physical property that changes abruptly near the equivalence point.

• primary standard

• titrant

• analyte

• indicator

• masking agent

The pH of the equivalence point of strong acid - strong base titration is not equal to 7.00 at 40°C.

• TRUE

• FALSE

If you want to determine the total minerals dissolved in a well water (Ca and Mg), what type of titration must be done?

• Acid-Base titration

• Precipitation titration

• Complexometric titration

• Redox Titration

Consider the titrations of the pairs of aqueous acids and bases listed on the left. For which pair is the pH at the equivalence point stated incorrectly?

• A

• B

• C

• D

• E

For the polyprotic acid H₃A, which of the equilibria below is INCORRECT?

• A^3- = HA^2- + OH^-

  K_b3 = K_w/K_a3

• H₂A^- = HA^2- + H⁺

  K_a2 = K₂

• HA^2- = A^3- + H⁺

  K_a3 = K₃

• H₃A = H₂A^- + H⁺

  K_a1 = K₁

• HA^2- = H₂A^- + OH^-

  K_b2 = K_w/K_a2

Methyl red is a common acid-base indicator. It has a K equal to 6.3 x 10^-6 . Its un-ionized form is red and its anionic form is yellow. What color would a methyl red solution have at pH = 7.8?

• blue

• green

• yellow

• red

• violet

The buffer needed for a capillary electrophoresis experiment must have a pH of 10.0. Which weak acid is the best choice for the buffer? Assume ionic strength is 0 M.

• ammonium chloride pKa = 9.24

• disodium phosphate pKa = 12.38

• 3-(Cyclohexylamino)propanesulfonic acid pKa = 10.40

• sodium dihydrogen borate pKa = 12.74

• cyclohexylaminoethanesulfonic acid pKa = 9.39