Acids, Bases, &

Saltsa modified presentation by Miss Nielsen

Activity

• 4 posters around the room.• 2 minutes with group at each poster• Write as many examples that you can think

of for the particular question on the poster paper

The Questions

• What are Properties of Acids?• What are properties of Bases?• What are some examples of Acids in daily

life?• What are some examples of Bases in daily

life?

What is an ACID?• pH less than 7• Neutralizes bases• Forms H

+ ions in solution

• Corrosive-• reacts with most metals to form

hydrogen gas• Good conductors of electricity

Common Acids • HCl- hydrochloric- stomach acid• H2SO4- sulfuric acid - car batteries

• HC2H3O2- acetic acid - vinegar

• H2CO3-carbonic acid – sodas

• H3PO4- phosphoric acid -flavorings

Weak vs. Strong Acids

• Weak Acids do not ionize completely: Acetic, Boric, Nitrous, Phosphoric, Sulfurous

• Strong Acids ionize completely: Hydrochloric, Nitric; Sulfuric, Hydriodic

What is a BASE?• pH greater than 7• Feels slippery• Dissolves fats and oils• Usually forms OH- ions in

solution• Neutralizes acids

Weak vs. Strong Bases

• Weak Bases: ammonia; potassium carbonate, sodium carbonate

• Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide

Common Bases

• NaOH- sodium hydroxide (LYE) soaps, drain cleaner• Mg (OH)2 - magnesium hydroxide-antacids

• Al(OH)3-aluminum hydroxide-antacids, deodorants

• NH4OH-ammonium hydroxide- “ammonia”

Acids and Bases in Solution• HCl + H20 H3O + + Cl-

(more hydronium ions, more acidic)• NaOH in water Na+ + OH-

(more hydroxide ions, more basic)• NaOH + HCl NaCl + HOH

Acid + Base yields type of salt and water

• NH3 + H20 NH4+ + OH- ammonia

gas + water yields ammonium and hydroxide ions

Theories of Acids and Bases

• In the 1800’s chemical concepts were based on the reactions of aqueous solutions.

• Svante Arrhenius (Mr. Deis’s favourite Swedish Chemist) developed a concept of acids and bases relevant to reactions in H2O.

• Arrhenius acid – produces hydrogen ions in water.• Arrhenius base – produce hydroxide ions in water.

Theories of Acids and Bases

Other Theories discussed further in your chemistry careers:

Bronsted-Lowry acid- donates a hydrogen ion/proton in a reaction.

Bronsted – Lowry base – accepts a hydrogen ion/proton in a reaction.

Lewis Acid – electron pair acceptor

Lewis Base – electron pair donator

Examples of Arrhenius Acids/Bases

• HNO3

• KOH• Ba(OH)2

Neutralization Reaction

• A neutralization reaction is the reaction of an acid with a base to produce salt and water.

• Example

H2SO4 + NaOH NaHSO4 + H2O

What is a SALT?• A salt is a neutral substance produced from the

reaction of an acid and a base.• Composed of the negative ion of an acid and the

positive ion of a base.• One of the products of a Neutralization Reaction• Examples: KCl, MgSO4, Na3PO4

Textbook Questions

• p.711,# 2,16,17a Q. Write dissociation equations for the following Arrhenius acids and bases:• HNO3

• KOH• HClO4

• H3PO4

• Ba(OH)2

What is pH?

• Scale based on logarithmic values to measure how acidic or alkaline a substance is

• Traditional Scale from 0-14

pH of Common Substances

Timberlake, Chemistry 7th Edition, page 335

Calculating pH

• pH• Water has an equilibrium concentration of its two ions: • 1.00x10-7M H+

(aq) and 1.00x10-7M OH-(aq) 

• When one concentration rises, the other decreases by the same amount to re-establish equilibrium. 

• Developed by Swedish chemist, Soren Sorensen, the calculation for the pH of a solution is… 

• pH = -log10 [H+(aq)]

[H+(aq)] (mol L-1) pH1.0 x 10-7  1.0 x 10-6  1.0 x 10-5  3.5 x 10-7  1.0 x 10-4  3.5 x 10-7  

pH values: XX.YY (X=sig Y=not sig)

Calculating pH

• Introductory pH calculations• Calculate the pH when:

– A. [H+(aq)] = 3.0x10-5 M

• B. [H+(aq)] = 2.77x10-12 M

– [OH-(aq)] = 3.4x10-11 M (now, pOH and what

“14” means)• Calculate the pH for each:

– [H+(aq)] = 6.300x10-4 M

– [OH-(aq)] = 2.99x10-2 M

– [H+(aq)] = 13 M

– [OH-(aq)] =2.5 M

• Now…– When pH changes by 2, what does that do to the [H+

(aq)] ?

– pH = 5.77. Calculate the [H+(aq)] (a reverse operation!)

• Strong Acids– 0.20 M HCl. Find pH– 0.300M H2SO4. Find pH

– 4.6x10-8 M HNO3. Find pH

• Strong Base– 0.150 M NaOH. Find pH– 0.10 M barium hydroxide solution. Find pH– 5.70g of potassium hydroxide in a 100 mL solution. Find pH– Magnesium hydroxide has a pH = 13.40. Find the original

magnesium hydroxide concentration.• Neutral Ionic

– 0.10 M NaCl. Find pH

Textbook Questions

• Questions: p.713,#43,45,47,49,81,82

ACID/BASE CHEMISTRY IN REAL LIFE

Situations in which pH is controlled

• “Heartburn” – stomach is acidic, Tums (calcium carbonate) neutralizes stomach acid

• Planting vegetables and flowers – fertilizers control pH, plants have own pH (Spruce trees)

• Fish Tanks and Ponds – Fish require a certain pH to survive, without that pH, fish will not survive (Miss Nielsen has personal experience with this!)

• Blood – carbon dioxide in blood stream• Swimming pools – pH around 7.5 to maintain the proper

pH without having skin irritation

Acid Rain

Pollution in the air (sulfur dioxide, carbon dioxide, nitrogen dioxide) combines with water to form various acids.

.

Rapid changes in pH can kill fish and other organisms in lakes and streams.Soil pH is affected and can kill plants and create sinkholes

pH in the Digestive System• Mouth-pH around 7. Saliva contains amylase, an

enzyme which begins to break carbohydrates into sugars.

• Stomach- pH around 2. Proteins are broken down into amino acids by the enzyme pepsin.

• Small intestine-pH around 8. Most digestion ends. Small molecules move to bloodstream toward cells that use them

• Bile – pH around 8 created in liver, stored in gall bladder and is used to break down fats (which are acids),

Edible pH Scale

Review Videos Featuring Mr.Lederer

• http://ca.youtube.com/watch?v=dzXeb_jm9sQ&feature=related

• http://ca.youtube.com/watch?v=W_ALHNjFtMg&feature=related

• http://ca.youtube.com/watch?v=PqYySv1L60g&feature=related