Problem 46 - Introductory Chemistry Atoms First

Question

A molecule contains 5 carbon atoms and 12 hydrogen atoms. Is it saturated or unsaturated? Explain how you know.

Step-by-Step Solution

Answer

The molecule is saturated, as it contains 5 carbon atoms and 12 hydrogen atoms which fit the general formula for saturated hydrocarbons (CnH2n+2), specifically \( C_5H_{12} \).

Step 1: Write down the given values for carbon and hydrogen atoms

We are given that the molecule has 5 carbon atoms (C=5) and 12 hydrogen atoms (H=12).

Step 2: Test for saturation using the general formula of saturated hydrocarbons

To check if the molecule is saturated, we should substitute the given values of carbon atoms (C=5) into the general formula for saturated hydrocarbons, CnH2n+2. For n=5, the formula becomes: \( C_5H_{2(5)+2} = C_5H_{12} \) Since our given molecule has the same number of hydrogen atoms, it confirms that the molecule is indeed saturated.

Step 3: Conclusion

The molecule contains 5 carbon atoms and 12 hydrogen atoms, fitting the general formula for saturated hydrocarbons (CnH2n+2). Therefore, the molecule is saturated.

Key Concepts

Molecular Formula

The molecular formula is a notation that represents the types and numbers of atoms in a molecule.
For hydrocarbons, these typically consist of only carbon (C) and hydrogen (H) atoms.
The formula provides a quick way to understand the composition of the compound.
For example, a formula like \(C_5H_{12}\) indicates a molecule with five carbon and twelve hydrogen atoms.
This formula is crucial when determining if a molecule is saturated or unsaturated since it reflects the balance between the carbon content and hydrogen saturation.

Carbon Atoms

Carbon atoms are the backbone of many organic molecules, including hydrocarbons.
Each carbon atom can form four covalent bonds with other atoms.
This ability allows carbon to create long chains or ring structures, which are typical in hydrocarbons.
In the molecule given in the exercise, there are 5 carbon atoms.
These carbon atoms can form bonds with hydrogen atoms, other carbon atoms, and sometimes other elements.
Understanding the number of carbon atoms helps in determining the molecular structure and possible saturation status.

Hydrogen Atoms

Hydrogen atoms are one of the simplest and most abundant atoms, able to form a single covalent bond.
This property makes them key players in the structure of hydrocarbons.
In the context of hydrocarbons, hydrogen atoms saturate carbon chains by filling the available bonds left after carbon-carbon bonds are made.
For the molecule in our exercise, there are 12 hydrogen atoms.
Knowing this count helps in applying the formula for saturated hydrocarbons, validating whether all carbon bonds are filled.

Saturation Testing

Saturation testing involves checking if a molecule adheres to the standard formula for saturated hydrocarbons, which is \(CnH_{2n+2}\).
This formula indicates that a saturated hydrocarbon has the maximum number of hydrogen atoms bonded to carbon.
To test saturation, count the carbon atoms \((n)\) and calculate the expected number of hydrogen atoms using the formula.
Compare this with the actual number of hydrogen atoms in the molecule.
If they match, as they do in the molecule \(C_5H_{12}\) from the exercise, the molecule is saturated.
This simple test helps quickly identify if a hydrocarbon is saturated or unsaturated.