Acid Rain

All life needs water to survive, but sometimes that

water is itself harmful

Acid Rain Objectives• Explain how rain can become acidified• Explain the damage done to life and structures

by acid rain• Design a lab to determine what type of rock is

the least affected by acid rain• Define and identify acids & bases based on

formula and properties• Determine the strength of an acid or base

using pH • Recognize health issues if your body pH is off

Water Cycle

What makes rain acidic?

Acid Rain is rain water that has been contaminated by an acid-forming gas

How acidic something is, is measured by its pH

• Pure Water has a pH of 7

• Normal Rain water has a pH of 5.6 (slightly acidic due to the CO2 in the air)

• “Acid” Rain has a pH lower than 5.6 (Usually between 4.5 and 5.5)

What causes Acid Rain?Natural Causes

Forrest Fires

Lightening Bolts

Volcanoes

What causes Acid Rain?Human Causes

Vehicles

Factories

Power Plants (especially coal burning ones)

These give off SOx and NOx!

• SO2 + H2O H2SO3 (sulfurous acid)

• SO3 + H2O H2SO4 (sulfuric acid)

• NOx + H2O HNO3 (nitrous acid)

What happens to life when exposed to acid rain?

Over time…..• Lakes and rivers can become

so acidic that fish eggs and other marine life are killed

• Soil can become so acidic that plants lose their leaves or needles and die

What happens to structures when exposed to acid rain?

Over time…..• The acid reacts with metals corroding them• The acid reacts with some types of stone

eroding it.

Think, Pair, Share

How come this is considered a Global Issue?

(Hint: Why would Canada care how much pollution the factories in the USA give off?)

Does the rain fall where the pollution is made?

Lab Time!

Design a Lab to determine what rock type is least affected by acid rain!

More About Acids and Bases!

Acid – ionic compound that produces hydrogen ions (H+) when dissolved in water.

Base – ionic compound that produces hydroxide ions (OH-) when dissolved in water

ACIDS

The formula for an acid starts with an H.

(Example: HCl)

Stronger acid = more hydrogen (H+) ions

Acetic acid HC2H3O2 Vinegar

Carbonic acid H2CO3 Carbonated beverages

Hydrochloric acid HCI Digestive juices in stomach

Nitric acid HNO3 Fertilizer production

Phosphoric acid H3PO4 Fertilizer production

Sulfuric acid H2SO4 Car batteries

BASES

The formula for a base ends with an OH. (Ex: NaOH)

Stronger base = more hydroxide (OH-) ionsAnd fewer H+ ions

Add Base to Water

OH-OH-

OH-

OH-

Na+

Na+Na+

Na+

NaOH Na+ + OH-

Aluminum hydroxide Al(OH)3 Deodorant, antacid

Calcium hydroxide Ca(OH)2 Concrete, plaster

Magnesium hydroxide Mg(OH)2 Antacid, laxative

Sodium hydroxide NaOH Drain cleaner, soap production

WATER

Water is H2O but can be written HOH! A small number of the molecules can ionize:

Since it makes equal amounts of H+ and OH- it is neither and acid nor a base…. Its NEUTRAL!

HOH H+ + OH-

AcidsAcidsAcidsAcids

Examples of AcidsVinegar HC2H3O2

Citrus fruits HC6H7O7

Stomach acid (HCl)

Characteristics of Acids•Tastes sour•Reacts strongly with metals•Conducts electricity in water•Indicator turns red

BasesBasesBasesBases Characteristics of Bases

• Tastes bitter• Conducts electricity in water• Turns red litmus paper blue• Generally slippery feel• Indicator turns blue

Examples of Bases*Lye (NaOH)

*Ca(OH)2

*KOH *Ammonia

* Bleach

NeutralizationNeutralization

HCl + NaOH HOH + NaCl(Hydrochloric Acid) + (Sodium Hydroxide) (Water) + (Salt)

Acid & Base salt & water

Sodium chloride NaCl Food flavoring, preservative

Sodium carbonate Na2CO3 Used to make glass

Potassium chloride KCl Used as a salt substitute to reduce dietary intake of

sodiumPotassium iodide Kl Added to table salt to

prevent iodine deficiency

Magnesium chloride MgCl2 De-icer for roads

Calcium carbonate CaCO3 Chalk, marble floors, and tables

Ammonium nitrate NH4NO3 Fertilizer, cold packs

pH ScaleMeasure of hydrogen (H+) ion concentration (The

lower the pH, the more H+ ions.)

What do these pH measurements show us about acid rain?

ReAciD B

aselue

Neutral – pH = 7 Neutral – pH = 7

Acid – pH = 0-6 Base – pH = 8-14

Demo Time!!

pH Matters!The Human Body: Enzymes

• Most enzymes work best at pH 7.2 (normal body pH)Exceptions include:– Pepsin (in stomach) acidic environment (pH of 2)– Pancreatic Amylase (in intestine) basic environment (8.2)

Think about it…

What organs maintain the pH

within your body?

Alkalosis vs. Acidosis

Acidosis – The body fluids have too

much acid.

Alkalosis – The body fluids have excess

base.

These tend to cause an imbalance between the CO2 and the sodium carbonate in your body.

Symptoms of Alkalosis

Acidosis

www.chem4kids.com www.pasco.comfaculty.fmcc.suny.edu creekconnections.allegheny.edu www.lcesc.k12.oh.uswww.tennislifemagazine.comPhysical Science Concepts In Action Textbook

Works Cited