Analytical Chemistry: Monoprotic Acid-Base Titration

1.

Multiple Choice

2 mins

1 pt

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

A

B

C

D

E

2.

Multiple Choice

2 mins

1 pt

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.

3.

Multiple Choice

2 mins

1 pt

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.

4.

Multiple Choice

2 mins

1 pt

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

primary standard

titrant

analyte

indicator

masking agent

5.

Multiple Choice

2 mins

1 pt

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

TRUE

FALSE

6.

Multiple Choice

2 mins

1 pt

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

7.

Multiple Choice

2 mins

1 pt

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

8.

Multiple Choice

2 mins

1 pt

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

9.

Multiple Choice

2 mins

1 pt

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

10.

Multiple Choice

2 mins

1 pt

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

11.

Multiple Choice

2 mins

1 pt

A compound available in high purity, does not decompose under ordinary storage conditions and stable while being dried by heating or vacuum is a:

primary standard

secondary standard

standard solution

indicator

titrant

12.

Multiple Choice

2 mins

1 pt

Which of the following combinations cannot produce a buffer solution?

HNO2 and NaNO2

HCN and NaCN

HClO4 and NaClO4

NH3 and (NH4 )2SO4

NH and NH Br

13.

Multiple Select

2 mins

5 pts

For the graphical equivalence point determination for a titration analysis, which of the following is(are) TRUE?

I. The steepest slope of the titration curve is the equivalence point.

II. The equivalence point occurs where the first derivative of the titration curve reaches its largest value.

III. The equivalence point occurs where the second derivative of the titration curve equals zero.

None of the above.

14.

Multiple Choice

2 mins

1 pt

25.0 mL of a 0.100 M solution of NH3 is titrated with 0.250M HCl. After 25.0 mL of the HCl has been added, the resultant solution is

Basic and before the equivalence point

Basic and after the equivalence point

Acidic and before the equivalence point

Acidic and after the equivalence point

Neutral and at the equivalence poin

15.

Multiple Choice

2 mins

1 pt

Which of the following terms is INCORRECTLY defined?

titration error: the difference between the end point and the equivalent point

direct titration: titrant is added to analyte until reaction is complete

equivalent point: volume of titrant added in excess of the end point to change a physical property of the analyte solution

blank titration: titration performed without analyte to calculate titration error

standardization: titration of a known amount of analyte to determine the concentration of the titrant

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