Q: A student is asked to calculate the amount of $$K_2SO_4 ($$molar mass = 174 g/mol) required to prepare 500 mL of a 0.2 M solution. Which calculation is correct?

$$0.2 \times 0.5 \times 174 = 17.4 g$$

Question 1

Which of the following best describes the primary focus of Analytical Chemistry as introduced in this module?

Accepted Answer

The application of chemistry, physics, mathematics, and statistics to produce information about the composition of matter for problem-solving in industry, environment, and society.

Question 2

Which equation is used to calculate the pH of a buffer solution containing a weak acid and its conjugate base?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log \left( \frac{[\mathrm{A}^-]}{[\mathrm{HA}]} \right)$$

Question 3

A student needs to prepare 250 mL of 0.1 M NaCl solution from a 1.0 M stock solution. Which equation should be used to determine the volume of stock solution required?

Accepted Answer

$$C_1V_1 = C_2V_2$$

Question 4

Which of the following statements about gravimetric analysis is correct?

Accepted Answer

It determines the amount of analyte based on mass measurements and stoichiometry.

Question 5

During an acid-base titration, which point is defined as the equivalence point?

Accepted Answer

The point where the amount of acid equals the amount of base in moles, according to the reaction stoichiometry.

Question 6

Which of the following is a correct expression for the dissociation constant ($$K_a) of a $$weak acid $$HA in $$water?

Accepted Answer

$$K_a = \frac{[H^+][A^-]}{[HA]}$$

Question 7

A solution is prepared by dissolving 0.5 mol of acetic acid ($$CH_3COOH) $$and 0.5 mol of sodium acetate ($$CH_3COONa) in $$enough water to make 1 L of solution. What is the main function of this solution?

Accepted Answer

To act as a buffer and resist changes in pH upon addition of small amounts of acid or base.

Question 8

Which of the following best describes the principle of chromatography?

Accepted Answer

Separation of mixture components based on their different affinities for a stationary and a mobile phase.

Question 9

In UV-Visible spectroscopy, which law relates absorbance ($$A) to $$concentration ($$c) $$and path length ($$l$$)?

Accepted Answer

$$A = \varepsilon c l$$

Question 10

A student is asked to calculate the amount of $$K_2SO_4 ($$molar mass = 174 g/mol) required to prepare 500 mL of a 0.2 M solution. Which calculation is correct?

Accepted Answer

$$0.2 	imes 0.5 	imes 174 = 17.4 g$$

Question 11

Which of the following is a common source of systematic error in titrimetric analysis?

Accepted Answer

Consistent misreading of the burette due to parallax error.

Question 12

Which of the following is NOT a correct way to prepare a buffer solution?

Accepted Answer

Mixing a strong acid with a strong base.

Question 13

Which of the following best describes the function of an indicator in an acid-base titration?

Accepted Answer

To change color at a specific pH range, signaling the end point of the titration.

Question 14

Which of the following is the correct relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 15

A solution contains 0.1 M $$HCl$$ and 0.1 M $$NaCl. $$What is the pH of the solution?

Accepted Answer

$$\mathrm{pH} = 1$$

Question 16

Which of the following is a qualitative application of gas-liquid chromatography (GLC)?

Accepted Answer

Determining the identity of components in a mixture based on retention time.

Question 17

Which of the following is a correct definition of a primary standard in titrimetric analysis?

Accepted Answer

A highly pure, stable compound used to prepare a solution of known concentration.

Question 18

Which of the following is a key difference between HPLC and GC?

Accepted Answer

HPLC uses a liquid mobile phase, while GC uses a gas mobile phase.

Question 19

Which of the following best describes the role of calibration in instrumental analytical chemistry?

Accepted Answer

It converts the electrical signal from the instrument into an analyte concentration.

Question 20

A student is asked to balance the following redox reaction in acidic solution: $$MnO_4$$^- + $$Fe^{2+}$$ \rightarrow $$Mn^{2+}$$ + $$Fe^{3+}. $$Which is the correct balanced equation?

Accepted Answer

$$MnO_4$$^- + $$5Fe^{2+} + 8H$$^+ \rightarrow $$Mn^{2+}$$ + $$5Fe^{3+} + 4H_2O$

Analytical Chemistry 2BBF: Core Concepts and Study Guide

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