CHEM 335 Organic Chemistry Lab 2026/2027 | 100+ Exam Questions & Answers | IR, NMR, TLC, GC & Fischer Esterification

CHEM 335 2026/2027 is a 30-page organic chemistry laboratory exam preparation resource containing 100+ exam questions and answers, presented as already graded A+. The document focuses on the practical and analytical skills required to systematically identify organic compounds, combining chemical classification tests with laboratory techniques and instrumental methods. Major areas include functional-group identification, 2,4-dinitrophenylhydrazine (2,4-DNPH) and chromic acid tests, reflux, separatory-funnel extraction, Fischer esterification, theoretical and percentage yield calculations, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, thin-layer chromatography (TLC) and gas chromatography (GC). The opening material concentrates on systematic organic compound identification and qualitative functional-group analysis. Students are tested on selecting and interpreting classification tests for ketones, aldehydes and other organic functional groups, including the use of 2,4-DNPH, chromic acid/Jones reagent, bromine and potassium permanganate. The questions connect chemical-test results with spectroscopic evidence, helping students determine which observations can provide evidence for particular structural features. The laboratory-technique section provides detailed revision of reflux, liquid-liquid separation and Fischer esterification. It covers correct reflux operation, condenser function, controlling boiling and the reflux ring, separatory-funnel layers and product isolation. Fischer esterification questions include isoamyl acetate synthesis, limiting-reagent and theoretical-yield calculations, percentage yield, drying products with magnesium or sodium sulfate, oxygen-18 isotope tracing and selecting the correct alcohol and carboxylic acid required to synthesize a target ester. These experimental principles are consistent with the methods commonly described in standard organic laboratory references such as Pavia et al., Introduction to Organic Laboratory Techniques: A Microscale Approach. A substantial section is dedicated to infrared spectroscopy (IR/FTIR). Students review electromagnetic radiation, wavelength and wavenumber calculations, molecular vibration, changes in dipole moment, IR-active vibrations, the harmonic-oscillator model and characteristic functional-group absorption regions. Important reference ranges addressed include carbonyl-containing aldehydes/ketones around 1725 cm⁻¹, alkene absorptions around 1640 cm⁻¹, ether C–O absorptions around 1200 cm⁻¹, alcohol O–H regions around 3300 cm⁻¹ and alkyne regions around 2200 cm⁻¹. The material also covers dispersive IR instrumentation, NaCl/KBr optics, DTGS detectors and the Michelson interferometer used in FTIR. The NMR spectroscopy questions examine chemical shift, shielding, tetramethylsilane (TMS), chemically nonequivalent nuclei, integration and spin-spin splitting. Students learn how chemical environment determines chemical shift, adjacent coupled nuclei determine peak multiplicity and integrated signal intensity reflects the relative number of contributing nuclei. The material also includes molecular-formula interpretation and practical spectrum-based identification questions. Another major component covers thin-layer chromatography (TLC), including stationary and mobile phases, capillary action, sample spotting, chamber saturation, solvent level, Rf-related interpretation, reaction monitoring, purity assessment and visualization. The document compares visualization methods such as UV light, potassium permanganate, phosphomolybdic acid, iodine and 2,4-DNPH and distinguishes destructive from nondestructive visualization approaches. These principles align with the established theory of planar chromatography described in analytical chemistry references such as Skoog, Holler and Crouch, Principles of Instrumental Analysis. The final section provides extensive preparation for gas chromatography (GC). Topics include gas-liquid chromatography, stationary and mobile phases, capillary columns, carrier gases, volatility, polarity, retention behavior and chromatographic separation. Questions also examine flame ionization detection (FID), detector response, injection-port and column temperatures, retention times and the factors influencing separation of volatile components. Overall, the combination of laboratory procedure, calculations, qualitative analysis and IR, NMR, TLC and GC interpretation makes this resource particularly useful for practical examinations, laboratory quizzes and comprehensive CHEM 335 exam revision. Relevant Students: This document is most relevant to students enrolled in CHEM 335 or an equivalent undergraduate organic chemistry laboratory/analytical organic chemistry course. It can also support chemistry, biochemistry, pharmaceutical science, medicinal chemistry, chemical science, forensic science and other laboratory-based STEM students who need practice with organic compound identification, spectroscopy and chromatography. The uploaded document does not identify a university, so an institution should not be added to the title unless it can be verified. 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