Analytical Chemistry - Lecture on Volumetric Analysis

Introduction

• Focus: Volumetric Analysis
• Key concepts: Concentration units and Analytical Chemistry

Types of Analytical Chemistry

1. Qualitative Analysis
   • Identifying the type of material
   • Methods used: Acidic and Basic radicals identification, functional group determination
2. Quantitative Analysis
   • Determining the amount of material
   • Methods used: Volumetric, Gravimetric, Instrumental Analysis

Methods in Quantitative Analysis

1. Volumetric Analysis
   • Suitable for most materials
   • Provides accurate results with acceptable error margins
2. Gravimetric Analysis
   • Accurate but time-consuming
3. Instrumental Analysis
   • More accurate, used for specific scenarios

Standard Units in Analytical Chemistry

• SI Units: meter (m), Kelvin (K), gram (g), liter (L), mole (mol)
• Prefixes: kilo (10^3), mega (10^6), giga (10^9), milli (10^-3), micro (10^-6)

Scale of Analysis

• Macro Analysis: Sample size ~50 mg
• Semi-Micro Analysis: Sample size 10 - 50 mg
• Micro Analysis: Sample size <= 1 mg

Concentration Units

1. Percent Composition
   • % by Mass: (mass of solute / mass of solution) * 100
   • % by Volume: (volume of solute / volume of solution) * 100
   • % Mass by Volume: (mass of solute / volume of solution) * 100
2. Parts Per Million (ppm)
   • Used for small concentrations, similar to mg/L
3. Parts Per Billion (ppb)
   • Smaller scale than ppm
4. Mole Fraction (X)
   • Ratio of moles of solute to total moles in solution
5. Molarity (M)
   • Moles of solute per liter of solution (mass/molecular weight * 1000 / volume (mL))
6. Molality (m)
   • Moles of solute per kg of solvent
7. Normality (N)
   • Gram equivalents of solute per liter of solution
   • N = Molarity × Valency

Definitions and Calculations

• Mole: Contains Avogadro's number of particles (6.02 x 10^23)
• Molar Mass: Sum of atomic masses of all atoms in a molecule
• Equivalent Mass: Atomic or molar mass divided by valency
• Dilution Law: M1V1 = M2V2 (for molarity). Same for Normality
  • For dilution calculations to find new concentrations

Examples and Problems

1. Neutralization Reaction Calculation
   • N dilution law is used: N1V1 = N2V Polynomial 2 Normality simplifies 1:1 reactant relationships
2. Normality and Molarity Conversion
   • Normality = Molarity × Valency
3. Weight Calculation in Solution Preparation
   • Using molar mass and desired molarity, volume
4. Determining Normality from Specific Gravity and Percent Composition

Important Points

• Accurate unit conversion is crucial for volumetric analysis
• Understanding relationships between different concentration units aids in problem-solving
• Specific gravity helps relate mass to volume for liquid solutions

Concepts To Do and Review

• Practice calculating molarity, normality, and using dilution law
• Apply SI units correctly in different scenarios
• Understand the impact of valency on normality calculations