# Degrees of Unsaturation - Video Tutorials & Practice Problems

Hydrocarbons fall into two categories:Saturated and Unsaturated- and both of these terms describe the number of hydrogens that carbon is bonded to.

## Definition of Saturation

### The difference between saturated and unsaturated molecules.

The equation 2n + 2 (where n = #carbons) predicts the number of hydrogens that an organic molecule should contain to be considered saturated.

- If the total number of hydrogens < 2n + 2, then the molecule is unsaturated.

Are the following molecules saturated?

**Hint:** You can figure this out without using the 2n + 2 rule.

### Is the following molecule saturated?

### Is the following molecule saturated?

### Is the following molecule saturated?

## Predicting IHD Structurally

*IHD is also known as the *Degree of Unsaturation*.

### What index of hydrogen deficiency is.

Basically the IHD is an easy way for us to compare how unsaturated a molecule is compared to another.

- 1 IHD = Compound is missing 2 hydrogens.
- Rings/Double bonds = 1 IHD
- Triple Bonds = 2 IHD

What is the IHD of the following molecules?

### What is the IHD of the following molecule?

### What is the IHD of the following molecule?

### What is the IHD of the following molecule?

## Predicting IHD using Molecular Formula

Unfortunately, the structure of a compound will not always be drawn for us. In that case, we use the following technique.

### How to use IHD with molecular formula.

*****If your professor taught you a different method, that’s fine! Whatever helps you get the right answer.

### What is the IHD for C4H7Cl?

### Calculating IHD using molecular formula

### Calculating IHD using molecular formula

Awesome job. Now we know how to easily calculate and compare the number of hydrogens that are missing for all types of compounds.

###### Do you want more practice?

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