Beginner Topic 605 of 1102 Acids, Bases & Electrochemistry
Acid Rain
Rain acidified by sulfur and nitrogen oxides forming sulfuric and nitric acids.
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In-depth explanation of Acid Rain
Acid rain is precipitation with a pH below about 5.6, caused mainly by sulfur dioxide and nitrogen oxides released from burning fossil fuels. These gases dissolve in water and are oxidized to sulfuric acid and nitric acid, which fall with the rain. Acid rain damages forests, acidifies lakes, harms aquatic life and erodes limestone and marble buildings. Scrubbers on power station chimneys and catalytic converters in vehicles reduce the emissions that cause it. International agreements have also lowered emissions in many regions.
Going deeper: Acid Rain
Key ideas: Normal rain is pH about 5.6 due to dissolved CO2 (H2CO3). Acid rain is below 5.6, caused by SO2 giving H2SO4 and NOx giving HNO3. Reactions: SO2 + H2O gives H2SO3, then oxidation gives H2SO4. Damage: CaCO3 + H2SO4 gives CaSO4 + CO2 + H2O (marble, limestone), leaching Al3+ in soils, and fish kills below pH about 5.
Common mistakes and connections: Mistakes: stating that normal rain is pH 7, and mixing up acid rain with global warming or the ozone hole. Scrubbers, catalytic converters and low-sulfur fuels cut emissions. Hard-water and limestone regions have buffering capacity, so lakes with carbonate are less affected. Links to buffers and alkalinity.
Visualization of Acid Rain
Natural rain is slightly acidic at about pH 5.6 from dissolved CO2; SO2 and NOx emissions push acid rain to pH 4.3 and below. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Marble statues erode because calcium carbonate reacts with sulfuric acid: CaCO3 + H2SO4 -> CaSO4 + H2O + CO2.
Frequently asked questions about Acid Rain
What is Acid Rain?
Rain acidified by sulfur and nitrogen oxides forming sulfuric and nitric acids.
Is Acid Rain a beginner, intermediate or advanced topic?
Acid Rain is a beginner topic in Acids, Bases & Electrochemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Acid Rain?
Study these earlier topics in Acids, Bases & Electrochemistry first: Ion-Selective Electrodes, pH Meter, Hydrogen Production by Electrolysis.
What comes after Acid Rain?
The next topics in Acids, Bases & Electrochemistry are Ocean Acidification and Antacids.
Can I practise Acid Rain with quizzes?
Yes. The interactive lesson includes a self-check question on Acid Rain, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Acid Rain fits in Acids, Bases & Electrochemistry
Acid Rain is topic 95 of 105 in Acids, Bases & Electrochemistry.