Expand the following condensed formulas into their complete structural formulas.
`CH_3CH_2OH`

Explanation

To expand the condensed formula `CH3CH2OH` into its complete structural formula, follow these steps:

### Step 1: Identify the components of the condensed formula
The condensed formula `CH3CH2OH` can be broken down into three parts:
- `CH3` represents a carbon atom (C) bonded to three hydrogen atoms (H).
- `CH2` represents another carbon atom (C) bonded to two hydrogen atoms (H).
- `OH` indicates the presence of a hydroxyl group, which is characteristic of alcohols.

### Step 2: Count the total number of carbon and hydrogen atoms
From the condensed formula:
- There are 2 carbon atoms (C).
- The total number of hydrogen atoms is 6 (5 from the two carbon atoms and 1 from the hydroxyl group).

### Step 3: Draw the carbon skeleton
Start by drawing the two carbon atoms connected by a single bond:
```
C
|
C--C
```

### Step 4: Add the hydroxyl group (OH)
Attach the hydroxyl group (OH) to one of the carbon atoms. Since this is an alcohol, it is typically attached to the terminal carbon:
```
C
|
C--C--OH
```

### Step 5: Complete the hydrogen atoms
Now, add the remaining hydrogen atoms to satisfy the tetravalency of carbon (each carbon atom forms four bonds):
- The first carbon (C) has three hydrogen atoms attached.
- The second carbon (C) has two hydrogen atoms attached.
- The hydroxyl group (OH) contributes one hydrogen.

The complete structural formula will look like this:
```
H H
| |
H--C---C--OH
| |
H H
```

### Final Structural Formula
The complete structural formula for `CH3CH2OH` is:
```
H H
| |
H--C---C--OH
| |
H H
```
This compound is known as ethanol.

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