CPC Chemical Analysis & Techniques 3

Question 1

Which property of X-ray fluorescence (XRF) makes it useful for elemental analysis?

Accepted Answer

Each element emits characteristic secondary X-rays when excited

Answer

When primary X-rays excite atoms, each element emits characteristic fluorescent X-rays at wavelengths unique to that element, enabling identification and quantification.

Question 2

In HPLC, what is the difference between isocratic and gradient elution?

Accepted Answer

Isocratic maintains constant mobile phase composition; gradient changes it over time

Answer

Isocratic elution uses a constant mobile phase composition throughout the run, while gradient elution systematically changes solvent strength to improve separation of complex mixtures.

Question 3

What analytical technique uses the principle of inductively coupled plasma to excite atoms for emission detection?

Accepted Answer

ICP-OES

Answer

ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry) uses an argon plasma at ~6000-10000 K to excite atoms, which then emit characteristic light at element-specific wavelengths.

Question 4

In titration analysis, what is the equivalence point?

Accepted Answer

The point where moles of titrant exactly equal moles of analyte

Answer

The equivalence point is where the amount of titrant added is stoichiometrically equal to the analyte, representing complete reaction.

Question 5

Which spectroscopic technique provides information about the functional groups in an organic molecule through molecular vibrations?

Accepted Answer

Infrared (IR) spectroscopy

Answer

IR spectroscopy identifies functional groups based on characteristic absorption frequencies of molecular bond stretching and bending vibrations.

(CPC) Certified Professional Chemist Practice Test

(CPC) Certified Professional Chemist Practice Test

CPC Chemical Analysis & Techniques 3