Question

Why does the minimum in a plot of plate height versus flow rate occur at lower flow rates with LC than with GC?

Short answer

Longitudinal diffusion is responsible for the lowest in a plot of plate height against flow rate occurring at lower rates with LC than with GC.

Step-by-step solution

Step1. Given information

The reason for the minimum in a plot of plate height versus flow rate occurring at lower rates with LC than with GC is to be stated

Step2. Diffusion

LC stands for liquid chromatography, and GC stands for gas chromatography. Diffusion is the migration of a chemical from a high concentration region to a low concentration region. This phenomenon is common in liquids and gases because their particles move randomly from one location to another. It is a mass transfer process that is influenced by concentration.

Step3. Explanation

Band broadening in gas chromatography is caused by longitudinal diffusion. As a result, the plate height decreases. The molecules of a gas diffuse far more quickly than the molecules of a liquid. As a result, band broadening occurs at greater flow rates in GC than in LC, whereas minimum occurs at lower rates in LC than in GC.