Chemistry Test Analytical Chemistry 4

Question 1

In atomic absorption spectroscopy (AAS), what is the purpose of the hollow cathode lamp?

Accepted Answer

To emit element-specific radiation that the analyte atoms absorb

Answer

The hollow cathode lamp emits narrow, element-specific spectral lines that are absorbed by ground-state atoms of the same element in the flame or furnace.

Question 2

Which electroanalytical technique measures current as a function of applied potential while the analyte undergoes redox reactions?

Accepted Answer

Voltammetry

Answer

Voltammetry sweeps potential and measures the resulting current from oxidation or reduction of the analyte at the working electrode.

Question 3

What is the van Deemter equation used to optimize in chromatography?

Accepted Answer

Column plate height (efficiency) as a function of mobile phase velocity

Answer

The van Deemter equation (H = A + B/u + Cu) describes how plate height (band broadening) varies with mobile phase linear velocity, helping find the optimal flow rate.

Question 4

In NMR spectroscopy, what does chemical shift (δ, in ppm) indicate about a proton?

Accepted Answer

Its electronic environment and degree of shielding or deshielding

Answer

Chemical shift reflects the electronic environment around a nucleus; electron-withdrawing groups deshield protons, shifting them downfield (higher ppm).

Question 5

Which titration technique uses electrical conductance of the solution to determine the endpoint?

Accepted Answer

Conductometric titration

Answer

Conductometric titration monitors solution conductance, which changes as ions are consumed or produced, revealing the endpoint through a plot inflection.

Chemistry Practice Test

Chemistry Practice Test

Chemistry Test Analytical Chemistry 4