Q: A titration is performed using 0.100 mol dm$$^{-3}$$ NaOH to titrate 25.0 mL of a monoprotic acid. If 30.0 mL of NaOH is required to reach the endpoint, what is the molarity of the acid?

$$M_B = \frac{M_A V_A}{V_B} = \frac{0.100 \times 25.0}{30.0} = 0.083$$ mol dm$$^{-3}$$

Question 1

Which step in the titration process is illustrated by the third diagram (c) in the first image, and what does it signify?

Accepted Answer

The observation of a color change, signifying that the equivalence point has been reached.

Question 2

In the context of titrimetric analysis, what is the primary purpose of using an indicator?

Accepted Answer

To provide a visible signal (such as a color change) at or near the equivalence point.

Question 3

Which of the following best describes the complex shown in the second image?

Accepted Answer

A metal ion surrounded by ligands in a defined geometric arrangement, forming a coordination complex.

Question 4

Which property of EDTA makes it especially useful as a titrant in complexometric titrations?

Accepted Answer

It forms strong, stable complexes with most metal ions, especially those with higher charges.

Question 5

A titration is performed using 0.100 mol dm$$^{-3}$$ NaOH to titrate 25.0 mL of a monoprotic acid. If 30.0 mL of NaOH is required to reach the endpoint, what is the molarity of the acid?

Accepted Answer

$$M_B = \frac{M_A V_A}{V_B} = \frac{0.100 	imes 25.0}{30.0} = 0.083$$ mol dm$$^{-3}$$

Question 6

Which of the following is NOT a requirement for a primary standard used in titrant standardization?

Accepted Answer

It must be highly soluble in water and have a low molecular weight.

Question 7

A student is titrating Fe$$^{2+}$$ with MnO$$_4^- in $$acidic solution. The balanced equation is: $$5 Fe$$^{2+}$$ + $$MnO_4$$^- + 8 H^+ \rightarrow 5 Fe$$^{3+}$$ + Mn$$^{2+}$$ + 4 H_2O. If 25.0 mL of 0.0200 $$mol dm$$^{-3}$$ MnO$$_4^- is $$used to titrate 50.0 mL of Fe$$^{2+}$$, what is the molarity of Fe$$^{2+}$$?

Accepted Answer

$$M_{Fe$$^{2+}$$} = \frac{5 M_{$$MnO_4$$^-} V_{$$MnO_4$$^-}}{V_{Fe$$^{2+}$$}} = \frac{5 	imes 0.0200 	imes 25.0}{50.0} = 0.0500$$ mol dm$$^{-3}$$

Question 8

Which of the following statements about precision and accuracy in chemical analysis is correct?

Accepted Answer

A result can be precise but not accurate, or accurate but not precise.

Question 9

In a precipitation titration using silver nitrate to determine chloride, which indicator is commonly used and what is the observed color change at the endpoint?

Accepted Answer

Potassium chromate; yellow to red

Question 10

Which of the following best describes the role of a ligand in a complexometric titration?

Accepted Answer

A ligand is a molecule that binds to a metal ion to form a complex.

Question 11

Which of the following is a correct balanced half-equation for the reduction of permanganate in acidic solution?

Accepted Answer

$$MnO_4^- + 8 H^+ + 5 e$$^- \rightarrow $$Mn^{2+} + 4 H_2O$

Question 12

A 1.00 g sample of vinegar is titrated with 0.100 mol dm$$^{-3}$$ NaOH, requiring 28.8 mL to reach the endpoint. What is the percentage of ethanoic acid (MW = 60.0 g mol$$^{-1}) in $$the vinegar?

Accepted Answer

$$\% = 100 	imes \frac{0.1728}{1.00} = 17.28\%$$

Question 13

Which of the following is a suitable indicator for the titration of a strong acid with a weak base?

Accepted Answer

Methyl orange

Question 14

Which of the following is a real-world application of analytical chemistry in environmental science?

Accepted Answer

Measuring the levels of polychlorinated biphenyls (PCBs) in natural systems to assess risk to humans.

Question 15

Which of the following statements about the use of EDTA in complexometric titrations is correct?

Accepted Answer

EDTA forms the strongest complexes with metals of the highest charge.

Question 16

In a redox titration, which of the following best describes the function of starch as an indicator?

Accepted Answer

It forms a blue complex with iodine, indicating the presence of I$$_2 at $$the endpoint.

Analytical Chemistry: Titrimetric Methods and Calculations

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