The pH Scale• created in 1909• “potential of hydrogen” = pH• measures from 0 to 14

• 0 – 7 acid• 7 is neutral (pure water)• 7 – 14 is basic (also called alkaline)

pH is based on how many hydrogen ions there are

The pH scale is logarithmic.

lemon = 2 apple = 3

Lemons are 10 times more acidic than apples.

2005

A chemist from New Zealand invented a new, stable acid with a pH of -18!

Called carborane, it is 10 billion billion times stronger than pH of 1!

It can be used to increase the octane of gasoline and to make vitamins digestible.

Indicators = organic compounds that change color to indicate pH

Substances with pH of 12 and above or 2 and below are considered dangerous.

pH and Lab Safety

• Clean up a spilled acid with a base

• Clean up a spilled base with an acid

• Neutralization = chemical reaction between an acid and a base that produces a solution of salt and water with a pH of 7

pH and Life• Stomach Acid = pH ~1• Urine = pH 6.0• Sea Water = pH 8.4• Fresh Water = pH 6 – 8• Blood = 7.4

If pH changes by as little as 0.4, serious illness and death may result.

What do you call it when the stomach acid harms the stomach lining?

pH and the stomach

In 2005, a Nobel Prize in Medicine was awarded to the discoverers of the real cause of ulcers, a bacteria called helicobacter pylori. Dr. Marshall, from Australia, had previously been ridiculed for his theory of ulcers and treating them with antibiotics like any infection.

pH = ~1 pH = 10.5

pH and the Movies

Naturally Acidic Environments

Naturally Alkaline Environments

Soda Lake, Wyoming Mojave Desert, Soda Desert

What is acid rain?What is acid rain?

Precipitation with higher than normal amounts of nitric and sulfuric acids.

What causes acid rain?

• volcanoes and decaying vegetation put acid rain causing materials into the atmosphere

• burning of fossil fuels puts sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere

• these substances combine with water and oxygen in the atmosphere to produce acid rain

In the United States, about 2/3 of all SO2 and 1/4 of all NOx come from electric power plants.

Where does acid rain go?

• prevailing winds blow the material across state and national borders, sometimes over hundreds of miles

• In NJ, prevailing westerly winds bring acid rain from the midwest where there are a lot of electric generating plants.

As of 2000, the most acidic rain falling in the U.S. has a pH of about 4.3!

What are the effects of acid rain?

• acidification of lakes and streams

• damage to trees

• damage to soils

• speeds up the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures

• reduced visibility from haze and smog

• harm public health

How do we measure acid rain?

• Pure water has a pH of 7.0.

• Normal rain is slightly acidic, pH 5.6, because carbon dioxide (CO2) dissolves into it forming weak carbonic acid

• Monitoring stations record data about precipitation, including its pH

Hydrangea – pink in basic soil

Hydrangea – blue in acidic soil

What should we do about acid rain?

• Clean up smokestacks and exhaust pipes

• Use alternative energy sources

• Restore a damaged environment

Air Quality in NJ

NJDEP Bureau of Air Monitoring