Chemistry Test Analytical Chemistry 2

Question 1

Which technique separates compounds based on their different rates of migration through a stationary phase under a mobile phase?

Accepted Answer

Chromatography

Answer

Chromatography separates compounds by differential migration between stationary and mobile phases.

Question 2

In gas chromatography (GC), what is the role of the carrier gas?

Accepted Answer

It serves as the mobile phase to transport analytes through the column

Answer

The carrier gas (e.g., helium or nitrogen) acts as the mobile phase, moving analytes through the GC column.

Question 3

What does the retention time in chromatography indicate?

Accepted Answer

The time a compound takes to travel from injection to detection

Answer

Retention time is the elapsed time from sample injection to the peak maximum of a compound at the detector.

Question 4

Which type of electrode is used as a reference with a constant, known potential in electroanalytical measurements?

Accepted Answer

Calomel or Ag/AgCl electrode

Answer

The saturated calomel electrode (SCE) and Ag/AgCl electrode are common reference electrodes with stable, reproducible potentials.

Question 5

In Beer-Lambert Law (A = εbc), what does ε represent?

Accepted Answer

Molar absorptivity of the analyte

Answer

ε (epsilon) is the molar absorptivity, a substance-specific constant expressing how strongly a compound absorbs light at a given wavelength.

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