Final answer:
Neutralize used sulfuric acid before disposal, typically with a basic compound, and follow local environmental and safety regulations for its disposal after neutralization.
Step-by-step explanation:
When dealing with used sulfuric acid (H₂SO₄), it's important to handle it with care due to its corrosive nature. You should never pour used H₂SO₄ directly into the sink or trash. Instead, it should be neutralized and then disposed of according to local environmental and safety regulations.
Typically, a basic compound such as sodium bicarbonate (baking soda) can be used for neutralization. After neutralization, the harmless salts and water that are produced can be disposed of safely, often down the drain with plenty of water, though checking with local waste disposal requirements is essential.
In a school or laboratory setting, there will usually be specific protocols for disposing of chemicals which should be followed closely. When preparing chemical experiments, adding sulfuric acid to water is the correct method to avoid a reaction that is too vigorous, which could potentially lead to injury or chemical splatter.