Fundamentals of Photophysics and Infrared Spectroscopy

Posted by on Jun 20, 2026 in Chemistry | 0 comments

1. Principles of Infrared (IR) Spectroscopy

Infrared (IR) spectroscopy is an analytical technique used to determine the functional groups present within a molecule. When a molecule is exposed to infrared radiation, it absorbs specific frequencies that match its natural molecular vibrations, causing quantized transitions between vibrational energy levels.

The IR region of the electromagnetic spectrum useful for organic chemistry typically spans wavenumbers from 4000 cm⁻¹ to 400 cm⁻¹. Wavenumber

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Principles of Membrane Separation and Adsorption Processes

Posted by on Jun 19, 2026 in Chemistry | 0 comments

Membrane Separation Processes

Gel Polarisation Model in Ultrafiltration

During ultrafiltration, retained solutes accumulate at the membrane surface, forming a concentration polarisation layer. When solute concentration reaches a limiting value (gel concentration, Cg), a gel layer forms, acting as a secondary resistance. The permeate flux is given by: J = k · ln(Cg / Cb), where k is the mass transfer coefficient. Beyond a critical pressure, flux becomes pressure-independent. Flux can be improved by

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Essential Organic Reactions and Stereochemistry Principles

Posted by on Jun 15, 2026 in Chemistry | 0 comments

Claisen-Schmidt Reaction

Introduction: The Claisen-Schmidt reaction is a crossed aldol condensation between an aromatic aldehyde and an aldehyde or ketone containing α-hydrogen in the presence of a base to form α,β-unsaturated carbonyl compounds.

Reagents

  • Aromatic Aldehyde
  • Aldehyde or Ketone containing α-hydrogen
  • Sodium Hydroxide (NaOH) or Potassium Hydroxide (KOH)

Mechanism

  1. Formation of enolate ion from ketone.
  2. Nucleophilic attack on aldehyde carbonyl carbon.
  3. Formation of β-hydroxy carbonyl compound.
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Mechanical Advantage and Chemical Properties

Posted by on May 22, 2026 in Chemistry | 0 comments

Understanding the Three Classes of Levers

Levers are simple machines used to gain mechanical advantage.

First-Class Levers

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First-class levers change the direction of force. Changes direction of force. Changes direction of force.

  • Case 1: DIN = DOUT, FIN = FOUT, MA = 1. Benefit: Changes direction of force. Drawback: No force or distance benefits. Example: See-saw, Scissors.
  • Case 2: DIN < DOUT, FIN > FOUT, MA < 1. Benefit: DIN < DOUT. Drawback: FIN > FOUT. Example: Catapult.
  • Case 3: DIN >
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Nuclear Physics: Forces, Decay, and Energy Principles

Posted by on May 5, 2026 in Chemistry | 0 comments

Forces in the Nucleus

  • Gravity: Force of attraction.
  • Weak nuclear: Weak interaction.
  • Strong nuclear: Strong interaction.

The strong force is attractive at very short distances and repulsive at slightly longer distances as a residual effect of holding together electrons and nucleons. Isotopes have the same number of protons but a different number of neutrons.

Half-Life Calculations

Half-Life FormulaFinding Number of Half-Lives

N = N0 x (1/2)n

n = T / t1/2

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N = number of nuclei or mass remaining

N0 = start

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Principles of Electrochemistry and Ionic Solutions

Posted by on Apr 22, 2026 in Chemistry | 0 comments

Activity and Activity Coefficient

Activity (a): Activity is the effective concentration of species in solution.

Where:

  • a = Activity
  • γ = Activity coefficient
  • C = Concentration

For an ideal solution: a = C

For a real solution: a = γC

For an electrolyte: a = a₊ · a₋

Activity and Mean Ionic Activity of Electrolytes

For an electrolyte: a = (a₊)ν₊(a₋)ν₋

Mean ionic activity (a±): a± = (a)1/ν

Mean ionic activity coefficient (γ±): γ± = (γ₊ν₊ · γ₋ν₋)1/ν

For a 1:1 electrolyte: a±

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