CHEM 108 (chemistry practical manual)

CHM 108 Practical Manual

Overview

This manual contains detailed practical experiments for CHM 108 including organic and analytical chemistry techniques such as fractional crystallization, chromatography, hydrocarbon testing, functional group identification, and salt analysis. Each section is tailored to prepare students with hands-on lab experience and proper documentation skills.

Practical 1: Separation by Fractional Crystallization

Prelab Questions

Why is CuSO₄ more soluble in water than in organic solvent?
Why does solubility of solids increase with temperature?
Evaluate experimental errors in salicylic acid and copper sulfate recovery.

Experimental Summary

Mixture of salicylic acid and CuSO₄·5H₂O separated using solubility and cooling techniques to yield solid crystals. Analysis includes mass calculation and percentage recovery.

Practical 2: Separation Using Chromatography

Prelab Questions

Why do some substances travel further on chromatograms?
How can chromatography confirm aspirin synthesis?
Define: Moving Phase, Adsorption

Experimental Summary

Thin-layer chromatography of chloroplast extracts with measurement of R_f values. Students prepare chromatograms and record color band movement and separation.

Practical 3: Physical Properties of Hydrocarbons

Prelab Questions

Draw structural formulas: ethane, toluene, propane
Define: Hydrocarbon, Alkane, Alkene, Alkyne, Aromatic Hydrocarbon

Observations

Odor and water solubility of hexane, 1-pentene, and toluene
Solubility of hydrocarbons in each other
General statement about hydrocarbon solubility

Practical 4: Chemical Properties of Hydrocarbons

Tests Included

Reaction with bromine (substitution/addition)
Potassium permanganate test for unsaturation
Evaluation of kerosene and unknown hydrocarbons

Practical 5 & 6: Functional Group Tests (1 & 2)

Tests Conducted

Solubility tests with water, NaOH, and HCl
Ceric nitrate test for alcohols
Silver nitrate test for halides
2,4-DNPH test for aldehydes & ketones
Tollens test for aldehydes
Bromination test for alkenes

Analysis and conclusion based on positive or negative results from each functional group test.

Practical 7: Analysis of Soluble Salts

Cation & Anion Analysis

Flame test and litmus observation for cations (Na⁺, K⁺, NH₄⁺, Cu²⁺, Ni²⁺, Ba²⁺)
Use of silver nitrate, nitric acid, and BaCl₂ to identify common anions (Cl⁻, I⁻, CO₃²⁻, SO₄²⁻, CrO₄²⁻)
Identification of salts based on solubility rules and precipitation tests