8.3 Acid Deposition

Acid rain can release nitrates in the soil that wash into waterways and cause eutrophication.
Discuss the meaning of the term eutrophication and its impact on plant life.

Identify a metal whose toxic ions can be released into waterways from the effects of acid deposition.

Aluminium hydroxide can be dissolved out of rocks under acidic conditions and release aluminium ions into the environment. Formulate an ionic equation for the reaction.

Aluminium hydroxide is amphoteric and can react with alkalis to form aluminate salts. Formulate an equation for the reaction between aluminium hydroxide and sodium hydroxide.

Two of the four oxoacids found in acid deposition are sulfurous acid, H₂SO₃ and nitrous acid, HNO₂.

Write equations to show the formation of these oxoacids from sulfur and nitrogen.

State the name and formula of the conjugate base of sulfurous acid, H₂SO₃.

Suggest ways of decreasing the impact of sulfurous acid on the environment.

Identify two substances that can be affected by the corrosive effects of acid deposition.

Sulfuric(VI) acid, H₂SO₄, and sulfur dioxide, SO₂, are known components of acid deposition. Write equations for their reactions with calcium carbonate.

Calcium nitrate(V) can be detected in the run-off water from limestone buildings that have been impacted by acid rain.

Write an equation to account for its formation and suggest why this is particularly damaging buildings.

Aluminium has a protective oxide layer on its surface which can be weakened and damaged by the effects of acid rain.

Nitrogen oxides produced by combustion are largely nitrogen monoxide or nitrogen dioxide.

Draw Lewis diagrams for nitrogen monoxide and nitrogen dioxide and use the diagrams to explain the meaning of the term free radical.

Platinum and rhodium are found in catalytic converters and facilitate the conversion of Carbon monoxide and nitrogen monoxides to nitrogen and carbon dioxide.

Write an equation for the reaction and state the changes in oxidation state for each carbon and nitrogen.

Use your answer to part (c) and the bond enthalpy data given in Table 1 to determine the enthalpy change for the reaction between carbon monoxide and nitrogen monoxide.

Table 1

Acid deposition can be produced by the reaction of NO₂ in the atmosphere. State the equation for the reaction.

Natural sources as well as human activities can contribute the formation of acid deposition. Name one natural source of acid deposition.

Sulfur from volcanic eruptions can produce sulfurous acid, H₂SO₃, in a two step reaction.

Write equations for the reaction.

A sample of sulfur is converted to H₂SO₃ using the reactions in part (b). If the % yield in both reactions is 75% determine the mass of sulfur needed to make 2 dm³ of 0.05 mol dm^-3 H₂SO₃,

Studies show that sulfurous acid, H₂SO₃, does not actually exist in solution but is the result of an equilibrium between sulfur dioxide and water:

SO₂ (g) +  H₂O (l) ⇌  HSO₃^- (aq) + H⁺ (aq)

Write an equilibrium expression for this reaction and suggest, with a reason, whether sulphurous is likely to be strong or weak acid.