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 all new terms introduced in each chapter.

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

• Monosaccharides: Be able to identify and provide examples.

Chapter 4: Introduction to Organic Compounds

Structural Isomers and Functional Groups

Organic compounds are molecules primarily composed of carbon and hydrogen, often containing other elements such as oxygen and nitrogen. Understanding their structure is essential for predicting chemical behavior.

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

• Functional Groups: Specific groups of atoms within molecules that determine chemical reactivity, such as alcohols (-OH), aldehydes (-CHO), and carboxylic acids (-COOH).

• Geometric Isomers: Isomers with the same connectivity but different spatial arrangement due to restricted rotation, often seen in unsaturated fatty acids (cis/trans).

• 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: Enantiomers are important in biochemistry because they can have different biological activities.

Chapter 5: Thermodynamics

Energy, Reaction Diagrams, and Chemical Equilibria

Thermodynamics studies the energy changes that accompany chemical reactions and physical transformations.

• Thermodynamic Terms: Endothermic reactions absorb energy; exothermic reactions release energy. Enthalpy (ΔH) measures heat change, entropy (ΔS) measures disorder, and free energy (ΔG) determines spontaneity.

• Energy Activation Diagram: Illustrates the energy required to initiate a reaction and the energy difference between reactants and products.

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

• Calorimetry: Used to measure heat changes in reactions.

• Kinetics: Studies the rate of chemical reactions and factors affecting it, such as catalysts and temperature.

• Reaction Rate Equation:

$\text{Rate} = k[\text{Reactant}_1][\text{Reactant}_2]$

• Redox Reactions: Involve the transfer of electrons; oxidation is loss of electrons, reduction is gain of electrons.

• Condensation, Hydrolysis, Addition: Types of reactions important in organic and biological chemistry.

Example: Identify the oxidized and reduced species in the reaction: $\text{Cu}^{2+} + \text{Zn} \rightarrow \text{Cu} + \text{Zn}^{2+}$

Additional info: Endergonic reactions require energy input; exergonic reactions release energy.

Chapter 6: Carbohydrates—Life’s Sweet Molecules

Structure, Classification, and Biological Roles

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 the building blocks of more complex carbohydrates.

• Disaccharides: Composed of two monosaccharides joined by a glycosidic bond, e.g., sucrose (glucose + fructose), lactose (glucose + galactose).

• Polysaccharides: Long chains of monosaccharide units, such as starch, glycogen, cellulose, and chitin.

• Fischer and Haworth Projections: Methods for representing the 3D structure of sugars. Fischer projections are linear; Haworth projections are cyclic.

• Stereochemistry: Carbohydrates can have multiple chiral centers, leading to various isomers.

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

• Blood Types and Sugars: Blood type antigens are determined by specific oligosaccharide structures on red blood cells.

Monosaccharide	Structure Type	Example
Glucose	Aldose	Blood sugar
Fructose	Ketose	Fruit sugar
Galactose	Aldose	Milk sugar component

Example: Draw the Haworth projection for D-glucose and identify the anomeric carbon.

Additional info: Chitin is a structural polysaccharide found in the exoskeletons of insects and crustaceans.