Why is Henry's Law important in breath testing?

Henry's Law is significant in breath testing because it describes how gases dissolve in liquids. This principle is pivotal when considering how alcohol (ethanol) evaporates from the bloodstream into the alveolar air in the lungs. According to Henry's Law, the amount of gas that can be dissolved in a liquid is directly proportional to the pressure of that gas above the liquid and its solubility in that specific liquid.

In the context of breath alcohol testing, as a person exhales, the alcohol present in their blood enters the air in their lungs and is subsequently detected by the Intoxilyzer 8000. The law helps establish a reliable relationship that permits the conversion of the alcohol concentration detected in breath samples to blood alcohol concentration (BAC). This relationship is fundamental for ensuring that breath test results accurately reflect the individual's level of intoxication.

The other options do not effectively relate to the principles applied in breath testing. Temperature effects on alcohol concentrations and phase changes do not directly correlate to how the alcohol levels are determined from breath samples. The relationship between gas pressure and volume is part of the broader gas laws but does not specifically relate to the measurement of alcohol in breath tests as clearly as the dissolution of gases in liquids does.