What is Acid Rain
Acid rain is a broad phrase that refers to any sort of precipitation that contains acidic components, such as sulfuric or nitric acid, that fall on the ground in wet or dry forms from the atmosphere. Acid rain is also known by its other name, acid deposition. This includes acidic precipitation, snow, fog, hail, and even dust.
What causes Acid Rain
Acid rain is produced when Sulfur dioxide (SO2) and nitrogen oxides (NOX) are released into the air and spread by wind and air currents. SO2 and NOX combine with water, oxygen, and other molecules to generate sulfuric and nitric acids. They descend to the earth after combining with water and other substances.
Some of the SO2 and NOX that contribute to acid rain originate from natural sources such as volcanoes, but the vast majority is produced by the combustion of fossil fuels. Because SO2 and NOX can be carried large distances and across borders by the wind, acid rain is a problem for everyone, not just those who live near its sources.
Acid Rain Chemistry Questions with Solutions
Q1: Glass containers are not recommended for collecting rainwater samples. Why?
a) Glass containers are expensive
b) Glass containers are not easy to maintain
c) Glass containers affect the pH of the rainwater
d) All of the mentioned
Answer: c) Glass containers affect the pH of the rain water
Explanation: Because glass containers can alter the pH of rainwater, they are unsuitable for collecting rainwater samples.
Q2: What does the term “liming” mean?
a) Erosion of calcium carbonate(lime) zones in soil
b) Application of magnesium and calcium-rich substances to soil
c) Excessive growth of lemon trees in acid rain-prone regions
d) None of the mentioned
Answer: b) Application of magnesium and calcium-rich substances to soil
Explanation: Liming is used to neutralize acidic soils created by strong acidic precipitation, despite the fact that it inhibits plant growth.
Q3: Which of the following gases is the primary cause of acid rain?
a) Carbon dioxide and carbon monoxide
b) Sulphur dioxide and nitrous oxide
c) Sulphur dioxide and nitrogen dioxide
d) Sulphur dioxide and carbon dioxide
Answer: b) Sulphur dioxide and nitrous oxide
Explanation: Sulfur dioxide and nitrogen dioxide have a high propensity to react with water to produce sulphuric and nitric acids, respectively.
Q4: The acidic air pollutants only reach the Earth’s surface because of wet deposition.
a) True
b) False
Answer: b) False
Explanation: Both wet and dry deposition can contribute to the formation of acidic air pollution at the surface of the Earth. Rain and humid weather induce wet deposition, but acidic pollutants and dust mixing cause dry deposition.
Q5: What pH is required for aquatic animals and plants to survive?
a) 7
b) 7.5
c) 4.8
d) 6.5
Answer: c) 4.8
Explanation: Aquatic organisms require a pH of 4.8, and if it falls below this level, it poses a threat to their survival.
Q6: What chemicals are involved in acid rain?
Answer:
Sulfur dioxide is produced by the combustion of fossil fuels. When it reaches the atmosphere, sulfur dioxide produces a sulfate ion. After combining with hydrogen atoms, the sulfate ion forms sulphuric acid. This results in acid rain.
Q7: How acidic is acid rain?
Answer:
Using the pH scale, acidity is determined. The range of the scale is from 0 to 14, with 0 representing the most acidic and 14 the most alkaline. Due to its interaction with natural substances, rain is always slightly acidic.
Q8: What can solve acid rain?
Answer:
Scientists have attempted to restrict emissions of sulfur oxide. This decreases the production of clean air. To restrict or prevent acid rain, scientists must cut sulfur oxides by 50%.
Q9: What Causes Acid Rain?
Answer:
Acid rain is produced when sulfur dioxide (SO2) and nitrogen oxides (NOX) are released into the air and transported by wind and air currents. SO2 and NOX react with water and oxygen to form sulfuric and nitric acids. They are then mixed with water and other substances before being released into the environment.
Some of the SO2 and NOX that contribute to acid rain originate from natural sources such as volcanoes, but the vast majority comes from the combustion of fossil fuels. The following are the most significant atmospheric sources of SO2 and NOX:
- Electricity is produced by the combustion of fossil fuels. Two-thirds of the SO2 and one-fourth of the NOX in the atmosphere are produced by power plants.
- Heavy equipment and automobiles
- Other industries include manufacturing and oil refining.
Wind can transport SO2 and NOX over long distances and across international boundaries, making acid rain a global problem.
Q10: Briefly describe different forms of acid rain deposition.
Answer:
Wet Deposition
Typically, acid rain is coupled with moist deposition. Skyward-formed sulfuric and nitric acids combine with precipitation, snow, fog, or hail to cause precipitation.
Dry Deposition
In the absence of moisture, acidic particles and gases can settle as dry deposition from the environment. Acidic particles and gases can easily settle on surfaces (water, vegetation, and structures) or react with bigger atmospheric particles, posing a threat to human health. When deposited acids are washed off a surface by the following rain, acidic water flows over and through the ground, harming plants, insects, and fish.
The amount of precipitation in a given region impacts the amount of acidity in the air that falls to the ground as dry deposition. For instance, arid regions have a greater proportion of dry to wet deposition than regions that receive a few inches of precipitation annually.
Q11: Explain the effects of acid rain on plants and trees.
Answer:
In areas hit by acid rain, dead or dying trees are frequent. Acid precipitation leaches aluminum from the soil Aluminum could be harmful to both plants and animals. Additionally, acid rain depletes the soil of vital minerals and nutrients required for tree growth.
At high elevations, acidic fog and clouds may deplete the nutrients in tree foliage, leading to brown or dead leaves and needles. Due to their diminished ability to absorb sunlight, the trees become weaker and less able to resist freezing conditions.
Nitrogen Pollution
The acidity of acid rain is not the only issue-causing component. Nitrogen is also included in acid rain, which can negatively impact particular ecosystems. For instance, nitrogen poisoning in our coastal waters is leading to the decline of fish and shellfish populations in certain locations. The majority of the nitrogen created by human activity that enters coastal waters comes from the atmosphere, agriculture, and sewage.
Absorption Capacity
Many forests, streams, and lakes are unaffected by acid rain because the acidity of the precipitation is neutralized by the soil in these areas. The thickness and composition of the soil, as well as the type of underlying bedrock, define its capacity. The thin soil in hilly regions of the northeastern United States cannot adequately neutralize the acid in rains. Due to this, these areas are more vulnerable, and acid and aluminum can accumulate in the soil, streams, and lakes.
Episodic Acidification
Due to snowmelt and intense rainfall, episodic acidity is possible. When melting snow or precipitation brings large quantities of acidic deposits and the soil is unable to act as a buffer, lakes that normally do not have a high acidity level may experience the effects of acid rain.
This brief period of increased acidity (lower pH) can impose short-term stress on the environment, leading to the death or harm of animals or species.
Q12: How to prevent or control acid rain?
Answer:
The following are some of the primary steps that must be followed to control acid rain:
1. Sulphur dioxide and nitrogen oxides in the atmosphere should be reduced.
i. Conserve energy (hence less fuel burnt)
ii. Use less polluting fuels
iii. Before release, remove sulfur and nitrogen oxides (Flue gas desulphurization and Catalytic Converters).
2. Use cleaner fuels
i. Coal with a low sulfur content
ii. “Washing” the coal to remove the sulfur
iii. Natural Gas
3. Flue Gas Desulphurisation (FGD)
i. Sulphur dioxide is removed from flue gas (waste gases)
ii. Contains a wet scrubber and a reaction tower with a fan that extracts hot, smokey stack gases from a power plant.
iii. Lime or limestone (calcium carbonate) is pumped into the tower as a slurry to mix with the stack gases and react with sulfur dioxide. Produces calcium sulfate that is pH-neutral and physically removed from the scrubber.
iv. Sulphates could be used for industrial applications
4. Use alternative power sources (i.e. nuclear power, hydroelectricity, wind energy, geothermal energy, and solar energy)
i. Cost issue
5. Liming to lessen the impact of Acid Rain
i. Acid neutralization with powdered limestone/limewater added to water and soil
ii. Utilised extensively in Norway and Sweden
iii. Expensive, temporary fix
Q13: Give the effects of SO2 and NOX on human health.
Answer:
Humans are no longer at risk from walking in acid rain or swimming in acidic lakes than walking in normal rain or swimming in non-acidic lakes. When pollutants that generate acid rain are present in the air, such as SO2 and NOX and sulfate and nitrate particles, they can be dangerous to humans.
Fine sulfate and nitrate particles are formed when SO2 and NOX combine in the atmosphere, which individuals can inhale. Many scientific investigations have found a link between these particles and effects on heart function, such as heart attacks that result in mortality in persons who have a higher risk of heart disease and impacts on lung function, such as breathing difficulties in people who have asthma.
Other Important Questions on Acid-Rain
Q.1 Which of the following gasses is responsible for the Taj Mahal’s yellowing?
- Organic carbon
- Black carbon
- Brown carbon
- All of the mentioned
Answer: All of the mentioned.
Q.2 Acid rain depletes
- Calcium
- Magnesium
- Both (A) and (B)
- None of the elements
Answer: [C] Both (A) and (B)
Q.3 What is the pH of rain in industrial zones?
- 4 to 5
- 3 to 7
- 4 to 8
- 2 to 4
Answer: [C] 4 to 5
Q.4 What does the term “liming” mean?
a) Application of magnesium and calcium-rich substances to soil
b) Erosion of calcium carbonate(lime) zones in soil
c) Excessive growth of lemon trees in acid rain-prone regions
d) None of the mentioned
Answer: [a] Application of magnesium and calcium-rich substances to soil
Explanation: Liming is done to neutralize soils that become acidic due to excessive acidic rainfall, but is known to have a harmful impact on plant life.
