Acid base reactions can have a strong environmental impact.
Acid rain reaction with marble.
Acid rain can damage buildings historic monuments and statues especially those made of rocks such as limestone and marble that contain large amounts of calcium carbonate.
How does acid precipitation affect marble and limestone buildings.
Acid rain has the following reaction with the marble calcium carbonate.
Acid rain contains carbonic nitric and sulfuric acid that are produced by oxidation and dissolution in water of gaseous oxides co 2 no 2 and so 2 present in the air as chemical pollutants.
Stone surface material may be lost all over or only in spots that are more reactive.
Caco 3 s h 2 so 4 aq caso 4 s co 2 g h 2 o l.
Caco 3 h 2 so 4 caso 4 h 2 o co 2 the formation of calcium sulphate results in the corrosion of this beautiful monument.
Marble and limestone both consist of calcium carbonate caco 3 a salt derived from the weak acid h 2 co 3.
It is well established that either wet or dry deposition of sulfur dioxide significantly increases the rate of corrosion on limestone sandstone and marble.
The damage that acid rain does to limestone and marble buildings and sculptures is due to a classic acid base reaction.
When sulfurous sulfuric and nitric acids in polluted air react with the calcite in marble and limestone the calcite dissolves.
Students know how to calculate ph from hydrogen ion concentration.
For example a dramatic increase in the acidity of rain and snow over the past 150 years is dissolving marble and limestone surfaces accelerating the corrosion of metal objects and decreasing the ph of natural waters.
Students know buffers stabilize ph in acid base reactions.
Acid precipitation affects stone primarily in two ways.
Acid rain effects on buildings acids have a corrosive effect on limestone or marble buildings or sculptures.
Acids in the rain react with the calcium compounds in the stones to create gypsum which then flakes off.
When sulfurous sulfuric and nitric acids in polluted air and rain react with the calcite in marble and limestone the calcite dissolves.
The reaction of a strong acid with a salt of a weak acid goes to completion.
Acid rains are one of the main degradation agents for marble artifacts.
Marble like all calcareous rocks is particularly sensitive to degradation by acid chemicals and to weathering.
How does this happen.
Students know how to use the ph scale to characterize acid and base solutions.
In exposed areas of buildings and statues we see roughened surfaces removal of material and loss of carved details.
