CHEM 1150 Exam 3 Study Guide: Organic Compounds, Thermodynamics, and Carbohydrates

General Exam Preparation

Overview

This study guide outlines key topics for CHEM 1150 Exam 3, focusing on organic compounds, thermodynamics, and carbohydrates. Students should review definitions, vocabulary, practice problems, and examples of sugars and monosaccharides.

• Definitions and Vocabulary: Understand key terms in each chapter.

• Practice Problems: Work through problems from class and homework.

• Monosaccharides: Know examples and properties.

Chapter 4: Introduction to Organic Compounds

Structural Isomers and Functional Groups

Organic compounds are molecules primarily composed of carbon and hydrogen, often containing functional groups that determine their chemical behavior.

• Structural Isomers: Molecules with the same molecular formula but different connectivity of atoms. For example, butane and isobutane.

• Functional Groups: Specific groups of atoms within molecules that are responsible for characteristic chemical reactions. Examples include alcohols (-OH), aldehydes (-CHO), and ketones (C=O).

• Geometric Isomers: Isomers with the same connectivity but different spatial arrangement due to restricted rotation, such as cis/trans isomers in alkenes.

• Chirality and Chiral Centers: A chiral center is a carbon atom bonded to four different groups, leading to non-superimposable mirror images (enantiomers).

Example: Draw the structural isomers for C4H10 (butane and isobutane).

Additional info: Unsaturated fatty acids contain one or more double bonds, which can lead to cis/trans isomerism.

Chapter 5: Thermodynamics

Energy, Chemical Reactions, and Equilibrium

Thermodynamics studies the energy changes that occur during chemical reactions and physical processes.

• Thermodynamic Terms: Endothermic (absorbs heat), exothermic (releases heat), enthalpy (ΔH), entropy (ΔS), energy, exergonic (spontaneous), endergonic (non-spontaneous).

• Energy Activation Diagram: Shows the energy changes during a reaction, including activation energy and transition state.

• Balancing Chemical Equations: Ensures the same number of atoms of each element on both sides of the equation.

• Calorimetry: Measurement of heat changes in chemical reactions. $q = m c  T$

• Kinetics: Study of reaction rates and factors affecting them, such as catalysts and temperature.

• Reaction Mechanisms: Stepwise sequence of elementary reactions by which overall chemical change occurs.

• Oxidation and Reduction: Oxidation is loss of electrons, reduction is gain of electrons. $\text{Oxidation: } \text{A} \rightarrow \text{A}^+ + e^-$ $\text{Reduction: } \text{B} + e^- \rightarrow \text{B}^-$

• Condensation, Hydrolysis, Addition: Types of reactions important in biochemistry. Condensation: Two molecules combine, releasing water. Hydrolysis: Water is used to break a bond.

Example: Draw an energy diagram for an exothermic reaction and label activation energy.

Additional info: Enzymes act as biological catalysts, lowering activation energy and increasing reaction rates.

Chapter 6: Carbohydrates—Life's Sweet Molecules

Structure, Classification, and Properties of Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, serving as energy sources and structural components in living organisms.

• Monosaccharides: Simple sugars such as glucose, galactose, and fructose. They are classified by the number of carbon atoms (triose, pentose, hexose) and functional group (aldose, ketose).

• Disaccharides: Composed of two monosaccharide units, e.g., sucrose, lactose, maltose.

• Polysaccharides: Long chains of monosaccharide units, e.g., starch, glycogen, cellulose, chitin.

• Fischer and Haworth Projections: Methods for representing the structure of sugars. Fischer projection: Linear form. Haworth projection: Cyclic form.

• Stereochemistry: Study of spatial arrangement of atoms. D- and L- forms refer to the orientation of the hydroxyl group on the chiral carbon farthest from the carbonyl group.

• Oxidation and Reduction of Sugars: Sugars can be oxidized to acids or reduced to alcohols.

• Blood Sugar Types: Glucose is the primary sugar in blood; other sugars may be present in certain conditions.

Example: Identify the monosaccharides in maltose (glucose + glucose), lactose (glucose + galactose), and sucrose (glucose + fructose).

Polysaccharide	Structure	Function
Starch	Branched (amylopectin) and unbranched (amylose) chains of glucose	Energy storage in plants
Glycogen	Highly branched chains of glucose	Energy storage in animals
Cellulose	Unbranched chains of glucose with β(1→4) linkages	Structural component in plant cell walls
Chitin	Chains of N-acetylglucosamine	Structural component in exoskeletons of arthropods

Additional info: Stereoisomers of sugars differ in the arrangement of atoms around chiral centers, affecting their biological activity.