Hazel Joan Tiago

Selah Grace Gumba

Acids and Bases

What are acids?What are bases?What are their physical and chemical behaviors?How are the strength of acids and bases identified?How are acids and bases quantified?What are pH indicators?What are common applications/ uses of acids and bases?

An acid  is a substance which reacts with a base. 

A solution that has an excess of H+ ions. It comes from the Latin word acidus or acere that means "sharp" or "sour".

Arrhenius definition:- Acids are substances which

increase the concentration of hydronium ions in solution.

Bronsted-Lowry definition:-Acid is an expansion: an acid is

a substance which can act as a proton donor.

Lewis definition:-Acids are electron-pair

acceptors.

A base in chemistry is an aqueous substance that can accept hydronium ions.

Bases are also the oxides or hydroxides of metals.

A soluble base is also often referred to as an alkali if hydroxide ions (OH−) are involved.

Arrhenius definiton:- sources of hydroxide anions

Bronsted- Lowry definition:-proton acceptor

Lewis Definition:- electron pair donors

Physical properties of acids

It has a sour taste. It turns blue litmus to red. It turns methyl orange to red. Acids are electrolyte. Strong acids destroy fabric. Strong acids cause burn on skin. Corrosive to metals Acids release a hydrogen ion into water

(aqueous) solution. Acids neutralize bases in a neutralization

reaction.

CHEMICAL PROPERTIES OF ACIDS

NEUTRALIZATION-An acid when reacts with a base, salt & water are produced. 

REACTION WITH CARBONATES

-Acid and carbonates are combined to produce salt, water and carbon dioxide

REACTION WITH BICARBONATES -Acid and bicarbonates are combined to produce salt, water and carbon dioxide

REACTION WITH METAL

Physical properties of bases

Slippery Turns red litmus to blue they react with most cations to

precipitate hydroxides taste bitter

STRENGTHS of ACIDS Strong Acids:

-completely dissociate in water, forming H+ and an anion.example: HN03 dissociates completely in water to form H+ and N031-.

The reaction is:HNO3(aq)  →   H+(aq) + N031-(aq)

There are only 6 strong acids: You must learn them. The remainder of the acids therefore are considered weak acids.

HCl

H2SO4 

HNO 3 

HClO 4

HBr

HI

Weak acids:-a weak acid only partially dissociates in water to give H+ and the anion

Anything that dissociates in water to produce H+ and is not one of the 6 strong acids

Molecules containing an ionizable proton. (If the formula starts with H then it is a prime candidate for being an acid.) Also: organic acids have at least one carboxyl group, -COOH, with the H being ionizable.

Anions that contain an ionizable proton. ( HSO41-  →   H+ + SO42- )

Cations:  (transition metal cations and heavy metal cations with high charge)

Also NH4+ dissociates into NH3 + H+

Weak bases:-a weak base only partially dissociates in water, making the reaction a reversible one.

STRENGTHS of BASES

Strong Bases-completely dissociate in water, forming

H+ and an anion.

Here are some examples of strong bases.

Ba[OH] 2

Ca[OH] 2

LiOH

KOH

NaOH

Sr[OH] 2

-Barium hydroxide

-Calcium hydroxide 

-Lithium hydroxide

-Potassium hydroxide

-Sodium hydroxide

-Strontium hydroxide

How are acids and bases quantified?

acids• monoprotic- has one ionizable proton per formula

• diprotic- having two ionizable hydrogens per formula (or two mols of ionizable hydrogen per mol of acid)

• triprotic- if there are three ionizable proton per formula

• polyprotic- any acid with two or more ionizable hydrogens

bases• monobasic- with one ionizable hydroxyl group

• dibasic- with two ionizable hydroxyl groups

• tribasic- with three ionizable hydroxyl groups

• polybasic- any material with two or more ionizable hydroxyl groups

What are pH indicators? A pH indicator is a material, usually an organic

dye, that is one color above a characteristic pH and another color below that pH.

There are many materials that can serve as pH indicators, each with its own ph range at which it changes color. Some have more than one color change at distinct pH's.

Litmus and phenolphthalein are common pH indicators. Litmus is red in acid (below pH 4.7) and blue in base (above pH 8.1).

What are common applications/uses of acids and bases?

dissociation

-is the separation of a molecule into ions, and it is a key factor for evaluating the "strength" of acids and bases. The more a substance is prone to dissociation, the better it can conduct an electric current, because the separation of charges provides a "pathway" for the current's flow.

Neutralization

- is the process whereby an acid and base react with one another to form a salt and water.

Example situation:

The human stomach produces hydrochloric acid, commonly known as "stomach acid." It is generated in the digestion process, but when a person eats something requiring the stomach to work overtime in digesting it—say, a pizza—the stomach may generate excess hydrochloric acid, and the result is "heartburn." When this happens, people often take antacids, which contain a base such as aluminum hydroxide (Al[OH] 3 ) or magnesium hydroxide (Mg[OH] 2 )

Titration

- the use of a chemical reaction to determine the amount of a chemical substance in a sample of unknown purity. Titration can also be used to measure pH ("power of hydrogen") level by using an acid-base indicator.

• Buffered solutions- is one that resists a change in pH

even when a strong acid or base is added to it. This buffering results from the presence of a weak acid and a strong conjugate base, and it can be very important to organisms whose cells can endure changes only within a limited range of pH values.

Acids & Bases

http://www.visionlearning.com/library/module_viewer.php?

mid=58

ChemTutor Acids & Bases

http://www.chemtutor.com/acid.htm

Reactions: Acids & Bases

http://www.chem4kids.com/files/react_acidbase.html

http://www.scienceclarified.com/everyday/Real-Life-

Chemistry-

Vol-2/Acid-Base-Reactions.html

ph indicators

http://chemistry.about.com/library/weekly/aa112201a.htm

common pH indicators

http://101science.com/PH.html

natural pH indicators

http://www.erowid.org/archive/rhodium/chemistry/eq

uipment/ph-

indicator.html

pH value

http://www.hach.com/fmmimghach?/CODE:LG0045861|

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Acids, Bases and pH Chemistry

http://chemistry.about.com/gi/dynamic/offsite.htm?

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s=80_2885_1020_615&f=00&tt=14&bt=1&bts=1&zu=ht

tp%3A//www.chem.vt.edu/RVGS/ACT/

notes/Notes_on_acids_and_bases.html