Lead acetate test paper is primarily used for detecting the presence of hydrogen sulfide gas. When exposed to hydrogen sulfide, the paper turns black due to the formation of lead sulfide. This makes it a valuable tool in various industries, including environmental monitoring, wastewater treatment, and oil and gas operations, where detecting hydrogen sulfide is crucial for safety and compliance. It is also used in laboratory settings for qualitative analysis in chemical experiments. The test paper offers a quick and simple method for identifying hydrogen sulfide leaks or contamination in different environments.