WHAT IS ACID RAIN?WHAT IS ACID RAIN?

• Generally, rain water has a pH value of 5.6 because of the carbon dioxide from air dissolved in it.

• Any rainfall has a pH value less than 5.6 is defined as acid rain.

• When gas pollutants e.g. sulphur dioxide, nitrogen dioxide

dissolve in rain water, various acids are formed.CO2 + H2O H2CO3 (carbonic acid)SO2 + H2O H2SO3 (sulphorous acid)NO2 + H2O HNO2 (nitrous acid) +

HNO3 (nitric acid)

CAUSES OF ACID RAINCAUSES OF ACID RAINSO2 : 70% NOx : 30%

X = 1 or 2

FORMATION OF FORMATION OF ACID RAINACID RAIN

SO2

NOX

SMOKE FROM FACTORIES

1.Vegetation1.Vegetation• Wash away essential nutrients

ions from soil• Poor growth of plants.

ENVIRONMENTAL ENVIRONMENTAL PROBLEMSPROBLEMS

2.Aquatic Life2.Aquatic Life

• Inflow of acidic water containing poisonous metal ions

• Kill the fish and water plants

3. Building3. Building• Acid rain attacks the building

materials and causes corrosion.

On-line ReferencesOn-line References

• http://igc.apc.org/acidrain/

• http://beakman.com/acid/acid.html

• http://qlink.queensu.ca/~4lrm4/

Your TaskYour Task

• Your town council is commissioning a new statue to be displayed downtown. You and your lab partner will conduct an experiment to investigate the effect of acid rain on various building materials in order to make a recommendation to the town council as to the best material to use for the statue. In your experiment, vinegar (pH 3) will simulate acid rain.

Research QuestionResearch Question

Of pea stone, red sandstone, and granite,

which material is the BEST for building a weather

resistant statute?

HypothesisHypothesis

If pea stone, red sandstone, and granite are subjected to acid rain

(pH 3) then granite will deteriorate the least because it is the most resistant to weathering.

Independent VariableIndependent Variable

Type of building material (pea stone, red sandstone, and

granite).

Dependent VariableDependent Variable

Difference in Remaining Mass (grams)

(final mass of stone – initial mass of stone)

Control GroupControl Group

Instead of acid rain test (submerge) the building materials (pea stone, red sandstone, and

granite) in tap (pure) water with a pH of 7.

Variables that must be kept constant

• Same amount of time in the vinegar (24 hours).

• same amount of vinegar (100 mL), same mass of building material (20 g).

• same balance. • same brand of vinegar.• same size container/lid.

Procedure

• Obtain a sample of each rock and record the mass of the sample in grams on the data table.

• Pour vinegar into each cup until the stone is completely covered.

• Let the stone sit for 24 hours. • Pour the vinegar out of each cup and mass the

stone. • Record the final mass of each type of stone in

the data table.• Subtract the original mass from the final mass of

each stone and record the data.

Data TableData Table

Type of Stone Mass Day 1 (grams)

Mass Day 2 (grams)

Pea stone

Red Sandstone

Granite