Acids: The term acid, in fact, comes from the Latin term acere, which means sour. Acids taste sour, are corrosive to metals, change litmus (a dye extracted from lichens) red, and become less acidic when mixed with bases.

Bases: Bases (also known as alkalies) feel slippery, change litmus blue, and become less basic when mixed with acids.

Acids and Bases

Neutralization: (Acid) + (Base) = (Salt) + (Water)

HCl + NaOH = NaCl + H2O

Where in the….S

What part of the tongue can taste a lemon or other sour things?

http://www.miamisci.org/ph/phplumber.html

Answer

The green areas are where you would taste sour foods such as a lemon.

Where in the….B

Where might you taste something bitter like baking soda?

Answer

The green area is where you would taste bitter foods such as baking soda.

This tells you how not to take those bitter pills.

Acid rain is rain that has been made acidic by certain pollutants in the air. Acid rain is a type of acid deposition, which can appear in many forms.

Wet deposition is rain, sleet, snow, or fog that has become more acidic than normal. Dry deposition is another form of acid deposition, and this is when gases and dust particles become acidic.

Both wet and dry deposition can be carried by the wind, sometimes for very long distances. Acid deposition in wet and dry forms falls on buildings, cars, and trees and can make lakes acidic. Acid deposition in dry form can be inhaled by people and can cause health problems in some people.

Acid Rain

Lifted from EPA website

                                                                                                    

                                          

pH-T

able

– E

PA

http://www.epa.gov/acidrain/site_students/phscale.html

Lemon Juice 4

Baking Soda 8

Aspirin 5

Ammonia 10

Milk of Magnesia 8

Lava Soap 10

Borax 9

Water 7

Lemon Soap 6

Vinegar 4

Tonic Water 4

Liquid Plumber 12

pH-Table continued

http://www.miamisci.org/ph/phplumber.html

[H+] pH ExampleAcids 1 x 100 0 HCl  - Hydrochloric acid

1 x 10-1 1 Stomach acid1 x 10-2 2  Lemon juice1 x 10-3 3  Vinegar1 x 10-4 4 Soda1 x 10-5 5 Rainwater1 x 10-6 6 Milk

Neutral 1 x 10-7 7 Pure waterBases 1 x 10-8 8 Egg whites

1 x 10-9 9 Baking Soda1 x 10-10 10 Tums® antacid1 x 10-11 11 Ammonia1 x 10-12 12 Mineral Lime - Ca(OH)2

1 x 10-13 13  Drano®

1 x 10-14 14 NaOH

pH-T

able

Indicators

Indicators-- An indicator is a special type of compound that changes color as the pH of a solution changes, thus Gives us an approximate pH of the solution.

Many dyes (chemicals) are sensitive to hydrogen-ion concentration. Beyond a certain threshold, they change visible color and are used as indicators of the relative pH of a solution.

Litmus paper - Paper with powder extracted from certain plants that tests the pH of a substance. Acid turns red while base turns blue; neutral remains white.

Phenolphthalein Phenolphthalein is a sensitive pH indicator

with the formula C20H14O4. Often used in titrations, it turns from colorless in acidic solutions to pink in basic solutions, the color change occurring between pH 8 and pH 10. If the concentration of indicator is particularly strong, it can appear purple.

http://en.wikimedia.org/wiki/Phenophthalein

Phenolphthalein is insoluble in water, and is usually dissolved in alcohol for use in experiments.

It is a colorless, weak acid, which can lose H+ ions in solution. However, the phenolphthalein ion is pink. When a base is added to the phenolphthalein, the [atom ion] equilibrium shifts to the ionization because H+ ions are removed.

Other indicators

Other indicators: Indicator pH of change Color @ lower pH Color @ higher pH

Methyl orange 4 Red Yellow Methyl red 5 Red Yellow Litmus 7 Red Blue Bromthymol blue 7 Yellow Blue Phenophthalein 9 Colorless Pink Alizarin yellow 11 Yellow Red

Make your own "litmus paper"

1. Chop the red cabbage up with a sharp knife. 2. Crush it with a "pestle and mortar" OR put it

in a food mixer and grind it. 3. Add a very small amount of water. 4. Decant the blue liquid (pour the liquid into a

clean glass). 5. Soak some blotting paper in the blue liquid. 6. Let the blotting paper dry out. 7. Cut the blue papers into small squares.

When you buy the red cabbage it is actually blue. It will be quite blue when you slice it up and add some tap water. That is because your tap water is very slightly alkaline. If you add some vinegar it will turn red. This is because there is a pigment (coloured chemical) in the red cabbage which acts as a pH indicator.

http://www.sambal.co.uk/indicators.html

Why is acid an acid?

All substances are made up of millions of tiny atoms. These atoms form small groups called molecules. In water, for example, each molecule is made up of two hydrogen atoms and one oxygen atom. The formula for a molecule of water is H2O. "H" means hydrogen, "2" means 2 hydrogen atoms, and the "O" means oxygen.

Why continued

When an acid is poured into water, it gives up H (hydrogen) to the water. When a base is poured into water, it gives up OH (hydroxide) to the water.

Stronger acids give up more protons (the positively charged parts of atoms); stronger bases give up more OH- (hydroxide). Neutral substances have an even balance of protons and OH-.

pH = - log10 [H+]

[H+] = hydrogen ion concentration in units of moles of H+ per liter of solution.

For example, a solution with [H+] = 1 x 10-7 moles/liter has a pH 7

a solution with [H+] = 1 x 10-6 moles/liter has a pH 6

A simpler way to think about pH is that it equals the exponent on the H+ concentration, ignoring the minus sign).

Quantitative description of pH

Human sense organs work logarithmically!!

Further Study

EPA: http://www.epa.gov/acidrain/site_students/whatisacid.html

http://www.shodor.org/unchem/basic/ab/#water

http://lrs.ed.uiuc.edu/students/erlinger/water/background/ph.html