Which is the best to use to determine if something is an acid or a base:

Phenothalein, universal indicator, or pH paper?

Agenda for Friday Oct 7th 1.Finish lab2.Acid/base notes3.Video

What is pH

• Def - A value used to express how acidic or basic something is

• Look at how many hydronium or hydroxide ions– H3O+ or OH-

pH Scale• the pH scale ranges between 0 and 14, with 7

being neutral

• A substance with a pH less than 7 is acidic.

• If greater than 7, the substance is basic or alkaline

• change in pH is a tenfold increase or decrease in the strength of the acid or base

Acid or base

• Acid – proton donor, increase in hydronium ions when added to water

• Properties– Sour in taste– Conducts electricity

Acid or base

• Base – proton acceptor, increase in hydroxide ions in water

• Properties– Bitter, soapy taste– Solutions feel slippery– Just as dangerous as acids

Acid – Base reactions

• Neutralization reaction – reaction with an acid and a base– Forms water and salt– Not all neutralization reactions produce neutral

solutions

Agenda for Monday Oct 10th 1. Neutralization of acid and base

Neutralizations

The “used” water problem

Agenda for Tuesday Oct 11th 1. Acid rain

Acid Rain

• Robert Angus Smith, an English chemist, first used the phrase "acid rain" in 1852 – noted the connection between London's polluted

skies and the acidity of rain

• "normal" rainfall has a pH of 5.6

• Acid rain is defined as any form of wet precipitation which has a pH less than5.6

Sources of Acid Pollution• gases sulfur dioxide and various nitrogen oxides– primarily created by industrial factories, coal-fired

power, plants, and car emissions• Some scientists believe that natural sources (forest

fires, lightning, volcanoes, etc.) have an equally important effect

Sources Continued

• Areas where the soil has been disturbed (mines, forest fires, landslides, construction sites) may be making water more acidic

• Many soils are already acidic or contain minerals which react with rainwater, snow melt, etc., to form acids.

• The gases SO2 and NOx are thought to be carried long distances by air currents.