SECTION 10.1: Reactivity

Overview

This subsection describes the chemical reactivity of the substance/mixture under normal conditions of use and foreseeable scenarios. It identifies potential hazardous reactions and conditions that could lead to dangerous chemical interactions.

Key Reactivity Factors

  • Inherent chemical stability
  • Oxidation/reduction potential
  • Polymerization potential
  • Thermal decomposition properties
  • Light sensitivity
  • Moisture sensitivity
  • Shock/friction sensitivity

Reactivity Hazard Classes (CLP Regulation)

Hazard Class Reactivity Characteristics Example Substances
Explosives Unstable structure with exothermic decomposition TNT, ammonium nitrate
Self-reactive Exothermic decomposition without oxygen Organic peroxides, azides
Pyrophoric Spontaneous ignition in air White phosphorus, alkyl metals
Water-reactive Violent reaction with water Sodium metal, calcium carbide
Oxidizing Releases oxygen promoting combustion Potassium permanganate, chlorates

Conditions to Avoid

  • Temperature ranges where decomposition/polymerization initiates
  • Exposure to incompatible materials (acids, bases, metals)
  • Contamination with catalytic substances
  • Static discharge or mechanical shock
  • UV/visible light exposure
  • Pressure changes

Hazardous Reaction Types

1. Decomposition Reactions

CaCO₃ → CaO + CO₂↑

May release toxic gases (e.g., HCN from nitrile decomposition)

2. Polymerization Reactions

Exothermic chain reactions requiring inhibitors (e.g., styrene polymerization)

3. Redox Reactions

2KMnO₄ + H₂SO₄ → K₂SO₄ + 2MnSO₄ + 3H₂O + 5O

Can generate reactive oxygen species

4. Acid-Base Reactions

Neutralization reactions generating heat (e.g., NaOH + HCl)

Material Compatibility Testing

Material Chemical Compatibility Temperature Rating Test Duration Test Method
316L Stainless Excellent -40°C to 150°C 30 days ASTM G31
PTFE Good -20°C to 260°C 60 days ASTM D543
PVC Fair 0°C to 60°C 45 days ASTM D543
Viton Excellent -15°C to 200°C 30 days ASTM D471

Reactivity Evaluation Methods

Testing Methods

  • Accelerated Rate Calorimetry: Measures self-heating rates under adiabatic conditions
  • DSC/TGA Analysis: Identifies exothermic peaks and decomposition temperatures

Example: Ethylene Oxide Reactivity Profile

Reactive Chemical Group Management

  • Peroxide Formers: Date containers and test quarterly
  • Air-Sensitive Materials: Use glove boxes or nitrogen purging
  • Shock-Sensitive Compounds: Store in cushioned containers