Introduction to IR Spectroscopy

How does IR spectroscopy help in identifying chemical compounds?

• By measuring the electrical conductivity of substances.

• By determining the boiling point of liquids.

• By analyzing the infrared light absorption of molecules to reveal their functional groups.

• By assessing the density of materials.

What types of samples can be analyzed using IR spectroscopy?

• Only solids can be analyzed.

• Solids, liquids, and gases.

• Only gases can be analyzed.

• Only liquids and gases can be analyzed.

How should solid samples be prepared for IR analysis?

• Place the solid sample directly in the IR beam without any preparation.

• Heat the solid sample until it melts and then analyze the liquid.

• Finely grind the solid sample, mix with KBr, and form a pellet or prepare a thin film.

• Dissolve the solid sample in water and analyze the solution.

What is the role of a potassium bromide (KBr) pellet in IR spectroscopy?

• KBr pellets serve as a transparent medium for solid samples in IR spectroscopy.

• KBr pellets enhance the color of the samples in IR spectroscopy.

• KBr pellets are used to cool samples before analysis.

• KBr pellets are used to dissolve liquid samples for testing.

How do you prepare liquid samples for IR spectroscopy?

• Place samples in a regular glass container

• Avoid filtering any samples

• Use a suitable solvent, place in an IR cell, ensure appropriate path length, and filter if needed.

• Use only water as a solvent

What is the significance of using a thin film for IR analysis?

• Thin films reduce the need for sample preparation.

• Thin films are only used for UV analysis.

• Thin films decrease the overall cost of analysis.

• Thin films improve sensitivity and resolution in IR analysis.

What precautions should be taken when handling samples for IR spectroscopy?

• Avoid contamination, use clean tools, ensure samples are dry, and use appropriate sample holders.

• Keep samples in humid conditions

• Store samples in open containers

• Use dirty tools for sample preparation

How does the sample's thickness affect the IR spectrum?

• Sample thickness has no effect on the IR spectrum.

• Thicker samples always produce clearer spectra.

• Sample thickness influences the intensity and resolution of the IR spectrum.

• Sample thickness only affects the color of the spectrum.

What is the importance of background subtraction in IR spectroscopy?

• It helps in identifying the molecular weight of compounds.

• Background subtraction is used to enhance color in IR spectroscopy.

• Background subtraction is important in IR spectroscopy to improve data accuracy by removing noise and interference.

• Background subtraction is essential for increasing sample size in experiments.

How can you ensure accurate results when introducing samples in IR spectroscopy?

• Ignore instrument calibration

• Use contaminated samples

• Handle samples inconsistently

• Use pure samples, prepare them correctly, calibrate the instrument, and maintain consistent handling.