Analytical Chemistry Overview

These flashcards cover fundamental concepts in analytical chemistry, detailing techniques such as chromatography, mass spectrometry, and NMR spectroscopy.

What is analytical chemistry?

The science of determining what a compound is, separating it out, and measuring how much of it there is.

What are classical methods used in analytical chemistry?

Methods such as titration, flame test, and chromatography that use known chemicals to react with unknown chemicals.

What is chromatography?

An analytical technique commonly used for separating a mixture of chemical substances into its individual components.

What is the function of the Rf value in chromatography?

The Rf value is the distance travelled by a component divided by the distance travelled by the solvent, used to identify substances.

What are the two phases involved in chromatography?

The stationary phase and the mobile phase.

What is gas-liquid chromatography?

A type of chromatography where the mobile phase is a gas and the stationary phase is a liquid adsorbed onto a solid.

How does the temperature of the column affect retention time in gas-liquid chromatography?

A higher temperature shortens retention times as it causes molecules to remain in the gas phase.

What influences the separation of compounds in gas-liquid chromatography?

The solubility of the compound in the liquid stationary phase and its tendency to remain in the gas phase.

What is the purpose of the detector in gas-liquid chromatography?

To record the output as a series of peaks, each representing the presence of a compound in the mixture entered into the machine.

What is mass spectrometry?

An analytical technique that separates ions based on their mass-to-charge ratio and identifies the presence of different atoms in a sample.

What does the term 'retention time' refer to in chromatography?

The time it takes for a particular compound to travel through the chromatography column to the detector.

Why is wet chemistry still in use despite the availability of instrumental methods?

Because the instrumentation is often very expensive, making wet chemistry a practical alternative.

What information can be derived from interpreting a mass spectrometer output?

The mass-to-charge ratios of different ions and their relative abundance.

What role do electronic transitions play in infrared spectroscopy?

They correspond to the vibrational and rotational states of molecules, causing characteristic absorption at specific frequencies.

How is NMR spectroscopy used in analytical chemistry?

NMR spectroscopy identifies different types of hydrogen atoms in a molecule based on their chemical environment.

What is the significance of tetramethylsilane (TMS) in NMR?

TMS is used as a reference compound in NMR, providing a baseline for measuring chemical shifts.

What is the principle behind the concept of 'fingerprint' in IR spectroscopy?

Unique spectral patterns specific to individual compounds allow for their identification.

What does the presence of the M+ peak indicate in a mass spectrum?

It corresponds to the molecular ion of the compound and its mass-to-charge ratio reveals the compound’s molecular mass.

What causes fragmentation in mass spectrometry?

The breaking of covalent bonds due to the energy absorbed when ions are generated.

How do greenhouse gases interact with infrared radiation?

They absorb and re-radiate infrared radiation emitted from the Earth's surface, contributing to greenhouse warming.

What is the role of the OH peak in NMR?

The OH peak is usually broad or may be missing, indicating the presence of hydrogen bonding in the sample.