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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?

what are ACIDS? 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.

Johannes Bronsted Thomas Lowry Gilbert Lewis

What are bases? 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 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 Examples of bases: •Slake lime •caustic soda

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? • 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

• monobasic- with one ionizable hydroxyl group 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).

dissociation What are common applications/uses of acids and bases? -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.

sources 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/equipment/ph- indicator.html

pH value http://www.hach.com/fmmimghach?/CODE:LG0045861|1//true Acids, Bases and pH Chemistry http://chemistry.about.com/gi/dynamic/offsite.htm?zi=1/XJ/Ya&sdn=chemistry&cdn=education&tm=198&gps=80_2885_1020_615&f=00&tt=14&bt=1&bts=1&zu=http%3A//www.chem.vt.edu/RVGS/ACT/ notes/Notes_on_acids_and_bases.html

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