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First teaching 2014

Last exams 2024

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Effects of Acid Deposition (DP IB Chemistry: SL)

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Effects of acid deposition

Effect on materials

  • Acid deposition can react with metals and rocks (such as limestone) causing buildings and statues to get damaged

 

The impact of acid deposition can be seen on buildings, statues and metallic structures, particularly in polluted cities

  • Limestone and marble both contain calcium carbonate
  • The calcium carbonate reacts with sulfuric or nitric acids causing stonework to corrode and weaken:

CaCO3 (s)  + H2SO4 (aq)  →  CaSO4 (aq)  +  CO2 (g)  +  H2O (l)

CaCO3 (s)  + 2HNO3 (aq)  →  Ca(NO3)2(aq)  +  CO2 (g)  +  H2O (l)

  • In addition dry deposition also affects limestone:

CaCO3 (s)  + H2SO4 (aq)  →  CaSO4 (aq)  +  CO2 (g)  +  H2O (l)

  • Metallic structures, such as iron bridges, are vulnerable to corrosion by wet and dry deposition forming the salt of the metal:

Fe (s)  + H2SO4 (aq) →  FeSO4 (aq)  +  H2 (g)

Fe (s)  + SO2 (g)  + O2 (g) →  FeSO4 (s) 

Effect on plants

  • Apart from acid deposition directly falling on leaves and killing plants, acid particulates can block stomata ( plant pores) and prevent gaseous exchange

 

The impact of acid deposition on plant life

  • Acid rain can fall on soils and release important minerals such as magnesium, calcium and potassium which are leached (washed out) from soils and are therefore unavailable to plants
  • Aluminium ions released from rocks are toxic to many plants and damage their roots

Effect on water

  • When acid rain falls on rivers and lakes the pH can fall to levels that are unable to support life

The impact of acid deposition on waterways

  • Below about pH 4, aluminium ions are released from rocks when they are held as aluminium hydroxide

Al(OH)3 (s) + 3H+ (aq)  Al3+ (aq)  + 3H2O (l)

  • Alumnium ions are toxic to fish as they damage the gills and prevent fish from efficiently absorbing oxygen
  • Nitrate ions from nitric acid in acid rain can contibute to over-fertilization of waterways and lead to eutrophication
    • Eutrophication is excessive algal growth that results in oxygen depletion and stagnation of waterways

Effect on human health

  • Although acid rain is too dilute to cause any direct impact on the skin, acidic particulates in the air can increase the risk of respiratory diseases such as bronchitis, asthma and emphysema
  • When acid rain comes into contact with metal pipes there is an increased risk that toxic metal ions will be released into the water supply such as Cu2+, Al3+ and Pb2+

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Stewart

Author: Stewart

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Exam Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.