ACS CP Analytical Chemistry & Instrumentation

Question 1

What is the purpose of a spectrophotometer in analytical chemistry?

Accepted Answer

Measure light absorption

Answer

A spectrophotometer is an analytical instrument used to measure the intensity of light absorbed by a sample at different wavelengths. By passing a beam of light through a solution and measuring how much light is transmitted versus absorbed, it can determine the concentration of a substance or identify specific compounds based on their unique absorption spectra.

Question 2

Which technique separates compounds based on their interaction with a stationary phase?

Accepted Answer

Chromatography

Answer

Chromatography is a powerful separation technique that separates components of a mixture based on their differential distribution between a stationary phase and a mobile phase. Components interact differently with the stationary phase (e.g., paper, gel, or packed column) and are carried along by the mobile phase at varying rates, leading to their separation. This allows for the analysis and purification of complex mixtures.

Question 3

In atomic absorption spectroscopy (AAS), what is measured?

Accepted Answer

Absorption of light by atoms

Answer

Atomic Absorption Spectroscopy (AAS) is an analytical technique used to determine the concentration of specific metal elements in a sample. It works by measuring the absorption of light at a specific wavelength by free atoms in the gaseous state. When light of the correct wavelength passes through a cloud of atoms, the atoms absorb some of the light, and the amount absorbed is proportional to their concentration.

Question 4

What does a pH meter measure?

Accepted Answer

Hydrogen ion concentration

Answer

A pH meter is an electronic device used to measure the pH of a liquid, which is a measure of its acidity or alkalinity. It works by measuring the activity of hydrogen ions (H+) in the solution. The meter displays this measurement as a pH value, providing a precise and rapid way to determine the solution's hydrogen ion concentration.

Question 5

Which analytical technique measures mass-to-charge ratios?

Accepted Answer

Mass spectrometry

Answer

Mass spectrometry is an analytical technique that ionizes chemical samples and then separates the resulting ions based on their mass-to-charge ratio (m/z). This separation allows for the identification of unknown compounds, quantification of known compounds, and elucidation of molecular structures by analyzing the fragmentation patterns.

(ACS CP) American Chemical Society (ACS) Certified Professional Practice Test

(ACS CP) American Chemical Society (ACS) Certified Professional Practice Test

ACS CP Analytical Chemistry & Instrumentation