acids and bases sections 8.3 and 8.4. acids a acid is a compound that produces hydronium (h 3 o + )...

ACIDS AND BASES

Sections 8.3 and 8.4

Acids

A acid is a compound that produces hydronium (H3O+) ions when dissolved in water.

Examples:HCl – hydrochloric acid

HNO3 – nitric acid

H2SO4 – sulfuric acid

(Notice the hydrogen in the front)

Properties of acidsTASTE SOUR

Things like lemons and oranges, taste sour because they contain acids. Do not test solutions by taste.

REACTIVE WITH METALSA metal changes color when exposed to a substance or bubbles form in a acid when a metal is placed in it.

CHANGE COLORS IN INDICATORSAn indicator is a substance that changes color in the presence of an acid or a baseOne type of indicator is Litmus paper. Litmus is a dye made from plants.Blue litmus turns red in the presence of an acid.Red Litmus stays red in the presence of an acid.

BASES

A BASE is a compound that produces hydroxide (OH-) ions when dissolved in water

Examples:NaOH – sodium hydroxide

Mg(OH)2 – magnesium hydroxide

Ca(OH)2 – calcium hydroxide

Notice the (OH) in each.

PROPERTIES OF BASESBITTER TASTE

Cough syrup has a base. Unsweetened (cooking) chocolate has a base in it to make it taste bitter.Again don’t test unknown substances by taste.

SLIPPERY FEELThink about soap when it gets wet.

CHANGES COLORS IN INDICATORS

Bases turn red litmus paper blue. Blue litmus stays blue.Phenolphthalein is another acid and base indicator. It turns red in base and stays clear in an acid.

ACID-BASE REACTIONS

A reaction between an acid and a base is called NEUTRALIZATION.

The reactants are an acid and a base.The products are water and a salt (contains a halogen)

An acid loses its hydrogen ion and is called a proton donor (b/c H+).A base loses its (OH) and is a proton acceptor (b/c OH -)

pH Scale

The pH is the measure of Hydronium ions in a substance

Ranges from 0-14

Low pH (0-6.99) is acidic.

High pH (7.01 -14) is basic

7 is neutral

Buffers and electrolytes

A Buffer is a solution that doesn’t allow big changes in pH.

Made from weak acids and weak bases.

An electrolyte is a substance that ionizes or separates into ions when it dissolves in water.

Made from strong acids or bases. Found in sports drinks

Strong and weak acids, bases

Strong acids dissolved in water, ionize almost completely.

Ph is low.

Strong bases dissolved in water, dissociate almost completely.

Ph is high.

Weak acids and bases ionize or dissociate slightly in water.

Ph is near neutral.