Skip to main content
Back

CHMY 123 Mid-term Practice: Organic Chemistry Concepts and Nomenclature

NotesPracticeVideo lessons

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Q1. Which one of the following properties is a property of alkanes?

Background

Topic: Properties of Alkanes

This question tests your understanding of the physical and chemical properties of alkanes, a class of hydrocarbons with only single bonds.

Key Terms:

  • Alkanes: Saturated hydrocarbons with only C–C and C–H single bonds.

  • Melting point: The temperature at which a solid becomes a liquid.

  • Density: Mass per unit volume; compared to water for organic compounds.

  • Solubility: Ability to dissolve in a solvent (e.g., water).

  • Chemical reactivity: How easily a compound undergoes chemical change.

  • Hydrogen bonding: Strong intermolecular force involving hydrogen and electronegative atoms.

Step-by-Step Guidance

  1. Recall that alkanes are nonpolar molecules and generally insoluble in water.

  2. Consider the trend in melting points and boiling points as the chain length increases.

  3. Think about the density of alkanes compared to water (most are less dense).

  4. Evaluate whether alkanes form hydrogen bonds or are chemically reactive.

  5. Identify which property listed is characteristic of alkanes.

Try solving on your own before revealing the answer!

Q2. What is the parent name of the following structure using IUPAC rules?

branched hydrocarbon structure

Background

Topic: IUPAC Nomenclature of Alkanes

This question tests your ability to identify the longest continuous carbon chain in a molecule and assign the correct parent name according to IUPAC rules.

Key Terms:

  • IUPAC: International Union of Pure and Applied Chemistry, sets rules for naming organic compounds.

  • Parent chain: The longest continuous chain of carbon atoms in a molecule.

  • Substituents: Groups attached to the parent chain.

Step-by-Step Guidance

  1. Examine the structure and count the longest continuous chain of carbon atoms.

  2. Ignore the branches for now and focus on the main chain.

  3. Compare the number of carbons in the main chain to the options given (ethane, butane, hexane, octane, pentane, hexamethylethane).

  4. Once you have identified the parent chain, match it to the correct IUPAC name.

Try solving on your own before revealing the answer!

Q3. A carbon-carbon double bond of an alkene consists of:

Background

Topic: Bonding in Alkenes

This question tests your understanding of the types of bonds present in a carbon-carbon double bond, specifically the sigma and pi bonds.

Key Terms and Formula:

  • Alkene: Hydrocarbon with at least one C=C double bond.

  • Sigma (\(\sigma\)) bond: Formed by head-on overlap of orbitals.

  • Pi (\(\pi\)) bond: Formed by side-to-side overlap of p orbitals.

Step-by-Step Guidance

  1. Recall that a double bond consists of one sigma bond and one pi bond.

  2. Understand how sigma and pi bonds are formed in the context of hybridization.

  3. Review the answer choices and identify which describes the correct bonding arrangement.

Try solving on your own before revealing the answer!

Q4. What is the IUPAC name of the compound shown?

branched alkane structure

Background

Topic: IUPAC Nomenclature of Alkanes

This question tests your ability to name a branched alkane using IUPAC rules, including identifying the parent chain and numbering the substituents correctly.

Key Terms:

  • Parent chain: Longest continuous carbon chain.

  • Substituents: Groups attached to the parent chain.

  • Numbering: Assign numbers to the chain to give substituents the lowest possible numbers.

Step-by-Step Guidance

  1. Identify the longest carbon chain in the molecule.

  2. Number the chain from the end closest to the first substituent.

  3. List the substituents and their positions.

  4. Combine the substituent names and positions with the parent chain name to form the IUPAC name.

Try solving on your own before revealing the answer!

Q5. How many secondary carbons are on the above molecule in question 4?

Background

Topic: Classification of Carbon Atoms

This question tests your ability to identify secondary carbons (carbons attached to two other carbons) in a branched alkane.

Key Terms:

  • Primary carbon: Attached to one other carbon.

  • Secondary carbon: Attached to two other carbons.

  • Tertiary carbon: Attached to three other carbons.

  • Quaternary carbon: Attached to four other carbons.

Step-by-Step Guidance

  1. Examine each carbon in the structure and count how many other carbons it is attached to.

  2. Identify and count all secondary carbons in the molecule.

  3. Compare your count to the answer choices.

Try solving on your own before revealing the answer!

Q6. Which of the following is an isomer of the molecule shown below?

branched hydrocarbon structure

Background

Topic: Structural Isomerism

This question tests your ability to recognize structural isomers—compounds with the same molecular formula but different connectivity.

Key Terms:

  • Isomer: Molecules with the same formula but different structures.

  • Structural isomer: Different connectivity of atoms.

Step-by-Step Guidance

  1. Determine the molecular formula of the given molecule.

  2. Compare the molecular formula to each option provided.

  3. Check if the connectivity of atoms is different but the formula is the same.

Try solving on your own before revealing the answer!

Pearson Logo

Study Prep