Introduction:
Breath analyzers are portable devices used by police to test the alcohol concentration in a person's breath. These devices work on the principle of acid-base reactions to detect the presence of alcohol.

Explanation:
1. Acid-base reactions:
Breath analyzers utilize acid-base reactions to determine the alcohol content in a person's breath. The alcohol present in the breath reacts with a chemical reagent in the breathalyzer, resulting in an acid-base reaction.

2. Chemical reaction:
The chemical reagent used in breath analyzers is typically a compound known as potassium dichromate. When alcohol from the breath comes into contact with this reagent, a chemical reaction occurs.

3. Oxidation of alcohol:
The main reaction that takes place is the oxidation of alcohol. The potassium dichromate acts as an oxidizing agent, and it oxidizes the alcohol present in the breath.

4. Color change:
During the oxidation process, the potassium dichromate changes color. Initially, it is orange in color, but as the alcohol gets oxidized, it turns green.

5. Detection:
The breathalyzer contains a sensor that detects the color change. This sensor can determine the alcohol concentration by measuring the extent of color change.

Advantages of using acid-base reactions:
- Acid-base reactions are relatively quick and can provide rapid results.
- They are simple and cost-effective compared to other types of reactions.
- Acid-base reactions are specific to alcohol, making them suitable for detecting drunken drivers.

Conclusion:
In conclusion, breath analyzers used by police to test drunken drivers work on the chemical basis of acid-base reactions. These reactions involve the oxidation of alcohol using a chemical reagent, resulting in a color change that can be detected by a sensor. Acid-base reactions are advantageous due to their speed, simplicity, and specificity for alcohol detection.