Acids/Bases/ & Acid Rain

How to Recognize Acids & Bases

• ACIDS BASES• H+ hydrogen ions OH- hydroxide ions w/ a metal*• Ex. HCl, H2SO4

, HNO3 Ex. NaOH, LiOH, Ca(OH)2,

• other ex.’s= citrus fruits *visual exception NH3(aq)

other ex= household cleaners• Acids taste sour Bases taste bitter

• Litmus test ends RED Litmus test ends Blue

How to measure STRENGTH of Acids and Bases

• pH scale: power of H+ ions

0 up to 7=Acidic 7= Neutral >7 to 14= BasicStrong Acids are near 0, Strong Bases near 14

Neutralization

• Acids react with Bases in a neutralization reaction to form water HOH (and a salt)

• Ex. HCl + NaOH HOH + NaCl• Pure water is neutral; equal concentrations of the H+ and OH-

ions• As OH- are added to H’s, HOH or water forms and the pH of the

solution “heads UP towards 7”• Ex. Start at pH=4 (acidic; more H’s than OH’s). Add OH-, water

forms and final pH can be 6• As H’s are added to OH’s, HOH or water forms and the pH

“heads towards DOWN towards 7”

Acid Rain Background

• CO2 + H2O H2CO3 carbon dioxide gas reacts with water to

form WEAK carbonic acid. Although slightly acidic, this is considered NORMAL rainwater

• SO2 + H20 H2SO4 sulfur dioxide gas reacts with water to

form sulfuric acid. This is highly acidic and = ACID rain. Rainwater with a pH less than 5.5 is considered Acid Rain. This gas enters the atmosphere mainly from coal power plants and industrial smokestacks

• NOx + H2O HNO3 nitrous oxides react with water to form

nitric acid. This is highly acidic and= ACID rain. These gases enter the atmosphere mainly from vehicle emissions

Acid Rain

Acid Rain’s Effect

Acid Rain and Lakes

Acid Rain and Forests

Acid Rain’s Effect on Stone

• Limestone and Marble w/CaCO3 is very susceptible to acid rain

• Sandstone, granite, and other materials without CaCO3 is Not affected by acid rain

• The lettering on this marble Stone has been weathered by acid rain