Acids And Bases 2

Acids and Bases Acids – compounds that ______ donate hydrogen ions (H+) to form hydronium ions (H3O+) in water. Ex. HCl + H2O → H3O+ + ClH+ + H2O → H3O+ (Hydronium ions are a combination of water and hydrogen ions) 1

Strong Acids – give off as many H+ ions as possible (ionize completely) Notice how all of the H+ ions split Weak Acids – give off ___ few H+ ions Notice how only some H+ ions split Acid Properties: Sour – ex. lemons Burn – ex. HCl (Stomach acid) Corrosive to metals 2

Common Acids ACID

FORMULA

STRENGTH

USES FOR DISSOLVED ACID

Hydrochloric acid (muriatic acid)

HCl

Strong

Cleaning and food processing adjusting the pH of swimming pools

Sulfuric acid

H2SO4

Strong

Making fertilizers and other chemicals; fluid inside car batteries

Nitric acid

HNO3

Strong

Making fertilizers and explosives

Acetic acid (ethanoic acid)

CH3COOH

Weak

Making vinegar; manufacturing chemicals, plastics, and medicines

Formic acid

HCOOH

Weak

Dyeing textiles

Citric acid

C6H8O7

Weak

Preparing flavorings, candies, and soft drinks

3

Bases – compounds that react with water to produce ____________ hydroxide ions OH-. (Not all bases contain hydroxide ions – ex. Ammonia NH3) Ex. KOH

K+ + OH-

Water is involved in the reaction, but does not react with the ions in this case.

4

Strong Bases – give off as many possible OH- ions as possible (completely ionize) Weak Bases – give off few OH- ions. Properties of Bases: Slimy / Slippery – ex. Cleaning products Bitter – ex. Mustard Corrosive to animal material (ex. Skin)

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Common Bases BASE

FORMULA

STRENGTH

USES FOR DISSOLVED BASE

Potassium hydroxide (potash)

KOH

Strong

Manufacturing soap and some drain cleaners; bleaching

Sodium hydroxide (lye)

NaOH

Strong

Manufacturing soap, paper, textiles, and some drain cleaners

Calcium hydroxide (lime)

Ca(OH)2

Strong

Making plaster, cement, and mortar

Ammonia

NH3

Weak

Manufacturing fertilizers and many cleaners

Methylamine

CH3NH2

Weak

Manufacturing dyes and medicines

Pyridine

C5H5N

Weak

Manufacturing vitamins and medicines

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Acids and Bases that are strong enough will _______________. conduct electricity (Electricity is the flow of electrons. If charges are present, like OHand H3O+, electrons can flow).

Left: ______ Strong Base Right: _____ Weak Base 7

pH Scale (powers of hydrogen) A measure of the hydronium ion (H3O+) concentration in a solution (and indirectly hydroxide, OH-, concentration).  Measures the _______ strength of an acid or base.  Range is 0 – 14 __  7 is neutral (not an acid nor a base)  0 – 7 is _____ acidic (lower is stronger) – 14 is basic (higher is stronger) 7 _____ 

8

9

Indicators – a compound that can change color in the presence of an acid or a base Common Indicators: Color in an Acid Color in a Base Red Litmus Paper Red Blue Litmus Paper Red Phenolphthalein

White

Blue Blue Pink

10

Neutralization Reaction – A reaction in which hydrogen ions (H+) from an acid, react with hydroxide ions (OH-) from a base to produce water salt. _____ molecules and a ____. Example: HCl

+

NaOH

→

?

How will the ions rearrange? H+ + Cl- + Na+ + OH11

H+ + Cl- + Na+ + OHHCl

+

Hydrochloric + Acid

NaOH Sodium Hydroxide

→

H 2O

+

→

Water

+

NaCl Salt

A pure salt water solution has a neutral ______ pH. This is why people eat Tums. Tums is a base, used to neutralize stomach acid.

12

Neutralization Reactions only completely neutralize if the amount and concentration of the acid and base are equal. Example: Will 5 mL of shampoo (pH 6) neutralize 50 mL of ammonia (pH 13)? No! The solution will only be slightly less basic.

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Use the following words / phrases to answer the following questions: • Strong • Weak • A lot of • A small amount of 1.To neutralize a strong acid, use ________ a lot of weak base. 2.To neutralize a weak acid, use the same amount of weak ____ base. 14

1.To neutralize a weak acid, use a small strong base. amount of _____ 2.To neutralize a strong _____ base, add the same amount of strong acid. a lot of 3.To neutralize a strong base, add ________ weak acid. 4.To neutralize a weak base, add a small amount of strong acid. _______________ 15