MChem Master of Chemistry Master of Chemistry: Analytical Chemistry 3

Question 1

Which titration method exploits the formation of a colored metal-indicator complex that is displaced by EDTA at the equivalence point?

Accepted Answer

Complexometric (chelatometric) titration

Answer

Complexometric titrations use metal indicators like Eriochrome Black T, which form colored complexes with metal ions that EDTA displaces at the endpoint.

Question 2

In atomic absorption spectroscopy (AAS), the hollow cathode lamp (HCL) is used because it emits:

Accepted Answer

Narrow-line radiation matching the analyte's absorption wavelength

Answer

The HCL emits narrow atomic lines of the same element as its cathode, perfectly matching the absorption profile of the analyte atoms.

Question 3

What is the primary advantage of using a standard addition method over external calibration in atomic spectrometry?

Accepted Answer

It compensates for matrix effects that alter the analytical signal

Answer

Standard addition compensates for matrix-matched suppression or enhancement because the standards experience the same matrix as the unknown sample.

Question 4

In cyclic voltammetry, what information is obtained from the ratio of the cathodic to anodic peak currents (i_pc/i_pa)?

Accepted Answer

The reversibility of the redox process

Answer

For a reversible one-electron process, i_pc/i_pa = 1; deviations indicate chemical reactions coupled to electron transfer (EC or CE mechanisms).

Question 5

Which separation mode in capillary electrophoresis is used specifically to separate neutral (uncharged) analytes?

Accepted Answer

Micellar electrokinetic chromatography (MEKC)

Answer

MEKC incorporates surfactant micelles as a pseudostationary phase that partitions neutral analytes, enabling their separation by electrophoresis.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Master of Chemistry: Analytical Chemistry 3