Deck 8: Let the Titrations Begin

Question 1

An aqueous mixture that is 0.100 M Ni²⁺ and 0.100 M Co²⁺ M is titrated with a 0.100 M CO₃²⁻.Which cation precipitates first and what is pCO₃²⁻ at the first and second equivalence points.K_sp = 1.0 x 10⁻¹⁰ for CoCO₃ and K_sp = 1.3 x 10⁻⁷ for NiCO₃.

Answer 1

Co²⁺ precipitates first,pCO₃²⁻ = 5.00,Ni²⁺ precipitates second,pCO₃²⁻ = 3.44

Question 2

Calculate pPb when 25.00 mL of 0.100 M CO₃²⁻ is titrated with 28.00 mL of 0.100 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

A)11.21
B)10.88
C)6)57
D)2)25
E)1)92

Answer 2

11.21

Question 3

Which of the following terms is INCORRECTLY defined?

A)titration error: the difference between the end point and the equivalent point
B)direct titration: titrant is added to analyte until reaction is complete
C)equivalent point: volume of titrant added in excess of the end point to change a physical property of the analyte solution
D)blank titration: titration performed without analyte to calculate titration error
E)standardization: titration of a known amount of analyte to determine the concentration of the titrant

Answer 3

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

Question 4

A NaOH solution is standardized using the monoprotic primary standard potassium hydrogen phthalate,KHP (204.22 g/mol. )If 0.6986 g of KHP requires 43.92 mL of NaOH,what is the NaOH concentration?

Question 5

For the graphical equivalence point determination for a precipitation reaction,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.

A)I only
B)II and III
C)II only
D)III only
E)I,II,and III

Question 6

Calculate pPb when 25.00 mL of 0.200 M CO₃²⁻ is titrated with 28.00 mL of 0.200 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

Question 7

A 1.9450 g sample containing only Na₂CO₃ and NaHCO₃ is titrated with 35.31 mL of 0.8724 M HCl.Calculate the percentage sodium carbonate and sodium bicarbonate.

A)43.53% Na₂CO₃;56.47% NaHCO₃
B)44.45% Na₂CO₃;55.55% NaHCO₃
C)55.55% Na₂CO₃;44.45% NaHCO₃
D)71.62% Na₂CO₃;28.38% NaHCO₃
E)56.47% Na₂CO₃;43.53% NaHCO₃

Question 8

Calculate pPb when 25.00 mL of 0.100 M CO₃²⁻ is titrated with 21.00 mL of 0.100 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

A)11.07
B)2)06
C)11.41
D)1)72
E)11.99

Question 9

The key step to titration calculations is to relate:

A)moles titrant to moles analyte.
B)volume titrant to volume analyte.
C)grams titrant to grams analyte.
D)conductivity titrant to conductivity analyte.
E)reduction titrant to oxidation analyte.

Question 10

Calculate pPb at the equivalence point when 25.00 mL of 0.120 M CO₃²⁻ is titrated with 0.120 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

Question 11

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

A)primary standard
B)titrant
C)analyte
D)indicator
E)masking agent

Question 12

Argentometric titrations are titrations using:

A)Au⁺.
B)Ag⁺.
C)Ar⁺.
D)Al³⁺.
E)As³⁻.

Question 13

A Na₂CO₃ standard solution is prepared by transferring 2.4817 grams of primary standard-grade sodium carbonate to a 250.0-mL volumetric flask,dissolving the sample in ~100 mL of distilled deionized water and diluted to the mark.A 25.00-mL aliquot is taken and titrated with 42.65 mL of HCl solution.Calculate the concentration of the HCl solution.

A)0)05490 M
B)0)1598 M
C)0)3196 M
D)0)1098 M
E)0)1997 M

Question 14

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

A)secondary standard.
B)primary standard.
C)standard solution.
D)indicator.
E)titrant.

Question 15

Common____________________ indicators are anionic dyes that are attracted to positively charged particles produced immediately after the equivalence point.

A)redox
B)absorption
C)acid-base
D)adsorption
E)complexometric

Question 16

The end point of some precipitation titrations for mixtures can be up to 3% high.The error is attributed to:

A)ion pairs.
B)coprecipitation.
C)turbidity.
D)solubility of the precipitates.
E)redox chemistry.

Question 17

The end point for the Volhard titration is indicated by:

A)adsorption of a colored indicator on the precipitate at the end point.
B)reduction of a colored indicator at the end point.
C)deprotonation of a colored acid-base indicator at the end point.
D)formation of a soluble,colored complex at the end point.
E)protonation of a soluble,colored complex at the end point.

Question 18

Calculate pPb when 25.00 mL of 0.150 M CO₃²⁻ is titrated with 17.00 mL of 0.150 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

Question 19

For the precipitation titration of analyte X⁻ by titrant M⁺,which of the following statements is NOT true?

A)Concentration M⁺ at the equivalence point is the molar solubility of MX or [M⁺] = .
B)Concentration M⁺ past the equivalence point is the excess M⁺ after reacting with all of the X⁻.
C)Concentration M⁺ before the equivalence point is the allowed M⁺ for the excess [X⁻] or [M⁺] = .
D)The plot of the titration curve is [M⁺] vs V_M⁺.
E)The titration reaction is M⁺ (aq)+ X⁻ (aq) $\rightarrow$ MX (s).

Question 20

Calculate pPb at the equivalence point when 25.00 mL of 0.100 M CO₃^2- is titrated with 0.100 M Pb²⁺.K_sp = 7.4 x 10⁻¹⁴ for PbCO₃.

A)5)17
B)7)96
C)6)57
D)4)87
E)8)26