Problem 67 - Chemistry The Molecular Science

Question

A cyclic hydrocarbon has 16 hydrogen atoms in each molecule. How many carbon atoms are there per molecule? What is the name of the compound?

Step-by-Step Solution

Answer

There are 8 carbon atoms; the compound is cyclooctane.

Step 1: Understanding the Problem

A cyclic hydrocarbon is a compound consisting only of carbon (C) and hydrogen (H) atoms, arranged in a ring structure. We need to find out how many carbon atoms are in the hydrocarbon given that there are 16 hydrogen atoms.

Step 2: Applying the Formula for Cycloalkanes

For a cyclic hydrocarbon, specifically cycloalkanes, the general formula is \( C_nH_{2n} \). This means if there are \( n \) carbon atoms, there will be \( 2n \) hydrogen atoms.

Step 3: Solving for Carbon Atoms

We have 16 hydrogen atoms, thus according to the formula \( C_nH_{2n} \), we set \( 2n = 16 \). Solving for \( n \), divide both sides by 2 to get \( n = 8 \). This means there are 8 carbon atoms in the molecule.

Step 4: Naming the Compound

A cyclic hydrocarbon with 8 carbon atoms is called cyclooctane. This name comes from combining 'cyclo', indicating a ring structure, with 'oct-' (from octa-, meaning eight) and '-ane', indicating a saturated hydrocarbon.

Key Concepts

Cycloalkanes

Cycloalkanes are a fascinating class of organic compounds known as cyclic hydrocarbons. These compounds consist of carbon and hydrogen atoms arranged in closed ring structures. Unlike their linear counterparts (alkanes), cycloalkanes have a distinctive shape due to the ring formation, which alters some of their chemical and physical properties.

• The general formula for cycloalkanes is \( C_nH_{2n} \), where \( n \) represents the number of carbon atoms.
• This formula indicates that for every carbon atom, there are twice as many hydrogen atoms.

Cycloalkanes are saturated hydrocarbons, meaning they only contain single bonds between the carbon atoms in the ring structure.
Cycloalkanes like cyclopropane, cyclobutane, cyclopentane, and cyclooctane, differ by the number of carbon atoms in their ring, influencing their stability and reactivity.
On a molecular level, the ring structure of cycloalkanes can cause a deviation from the ideal tetrahedral angle of 109.5 degrees, especially in smaller rings, leading to ring strain and unique chemical behavior.

Chemical Formulas

Chemical formulas are a methodical way of representing the composition of molecules. They tell us which elements are present and how many atoms of each element are found in a molecule.

• For example, the formula\( C_nH_{2n} \) for cycloalkanes reflects the specific ratio of carbon to hydrogen atoms in the molecule.
• "\( C_n \)" stands for a variable number of carbon atoms, while "\( H_{2n} \)" means there are exactly twice as many hydrogen atoms as carbon atoms.

When given a chemical formula, you can deduce important information about the molecule.For cycloalkanes, knowing the formula allows one to determine the number of carbon atoms based on the number of hydrogen atoms and vice versa.
In the exercise we've seen, when we know a cycloalkane has 16 hydrogen atoms, we can use the formula to find that the compound has 8 carbon atoms, making it cyclooctane.

Organic Chemistry

Organic chemistry is the branch of chemistry that studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds. This includes hydrocarbons like cycloalkanes, as well as compounds with a wide variety of other elements.

• It is fundamental in understanding life since all known life forms are based on organic compounds.
• Organic chemistry is essential in fields like pharmaceuticals, agriculture, and biotechnology.
• The study encompasses both simple molecules like methane and complex structures like DNA.

A strong grasp of organic chemistry enables chemists to synthesize new molecules, develop new materials, and create new drugs.
Understanding concepts like cyclic hydrocarbons and their chemical formulas is just a small but vital part of this extensive field. For instance, knowing how to apply the \( C_nH_{2n} \) formula for cycloalkanes helps predict reactions and understand the formation of different organic molecules.