Acids & BasesThey are everywhere..

In your foodIn your house

EVEN IN YOU!!!!!

What is an acid? An acid is a solution that has an

excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour".

The more H+ ions, the more acidic the solution.

Properties of Acids Taste sour Conduct electricity Corrosive, which

means they break down certain substances. Many acids can corrode fabric, skin, and paper

Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

Properties of Acids Some acids react

strongly with metals and form hydrogen gas

React with bases to form salts and water

Turn blue litmus paper red

Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

Uses of Acids Acetic acid - vinegar Citric acid - lemons, limes, &

oranges. Ascorbic acid - Vitamin C

which your body needs to function.

Sulfuric acid is used in the production of fertilizers, steel, paints, plastics, and in car batteries.

Hydrochloric acid – stomach acid

What is a base? A base is a solution that has an

excess of OH- ions. Another word for base is alkali.

Properties of a Base Feel slippery Taste bitter Caustic, which means

they break down certain substances.

Conduct electricity. (Think alkaline batteries.)

Properties of a Base Do not react with

metals. React with acids to

produce salts and water. Turns red litmus paper

blue.

Uses of Bases Bases – found in soaps,

ammonia, and many other cleaning products.

The OH- ions interact strongly with substances, such as dirt and grease.

Chalk and oven cleaner contain bases.

Blood is a basic solution.

Acids and Bases – electrical conductors

Acids and bases both can conduct electricity because both contain ions

Ionic solutions are electrolytes - any substance containing free ions that make the substance electrically conductive

pH Scale• pH is a measure of

how acidic or basic a solution is.

• The pH scale ranges from 0 to 14.

• Acidic solutions have pH values below 7

• Solutions with a pH of 0 are very acidic.

pH Scale• A solution with a pH of

7 is neutral.• Pure water has a pH of

7. • Basic solutions have

pH values above 7.• Solutions with a pH of

14 are very basic

pH Scale• A change of 1 pH unit represents a

tenfold change in the acidity of the solution.

pH Scale• For example, if one solution has a pH

of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.

The relationship between H+, OH- and pH

Weak vs. Strong Acids Strong acids ionize completely when placed in

water. HCl, HNO3, H2SO4, HClO4, HI, HBr HCl H+ + Cl-

Weak acids do not ionize completely, they remain mostly intact and release fewer H+ ions

CH3COOH ↔ CH3COO- + H+

Weak vs. Strong Baces Strong bases ionize completely when placed in

water. NaOH, LiOH, Be(OH)2, Mg(OH)2

Mg(OH)2 Mg2+ + 2(OH)-

Strong bases remove more H+ ions when they are mixed with water (the OH- ions react with the H + ions)

Weak bases do not ionize completely, they remain mostly intact and release fewer OH- ions and remove fewer H+ ions when they are mixed with water

NH3 + H2O ↔ NH4+ + OH-

Acid – Base Reactions A reaction

between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions.

Acids and Bases react to form salts When an acid and a base react, H+ ions and

OH- ions react to produce water and decrease the concentration of H+ ions

The anions and cations that were connected with the H+ ions and OH- ions react to form salts.

NaOH + HCl Na+ + Cl- + H+ + OH-

NaOH + HCl NaCl + H2O

Acid – Base reactions Each salt listed in

this table can be formed by the reaction between an acid and a base.

Salts are very important chemicals

Serial Dilution Serial dilution is the stepwise dilution of a

substance in solution.