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Acids and Bases GoalsAcids and Bases Goals

A. Explain the structure of the ppH scale.H scale.

B. Compare and contrast the components and propertiescomponents and properties of acids and bases.

C. Determine whether common household substances are acidic, basic, or neutral.acidic, basic, or neutral.

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The pH ScaleThe pH Scale

•Measurement Measurement system that system that indicates the indicates the number of H+ number of H+ ions in solution.ions in solution.

•pH comes from the Greek word potenz meaning power (and H for hydrogen).

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AcidsAcids are molecules that release hydrogen ions in solution.

HCl H+ + Cl-

BasesBases are molecules that either take up hydrogen ions or give off hydroxide ions in solution.

NaOH Na+ + OH-

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Characteristics of Characteristics of AcidsAcids

• pH less than 77• Produces hydrogen ions (Hhydrogen ions (H++)) in

solution.• When added to water H+ interacts

with the H2O to produce HH330 0 ++ (Hydronium ion)

• Taste sour• Corrosive• Look at page 767.

– What do all of the acids have in common?

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Characteristics of BasesCharacteristics of Bases•pH higher than pH higher than 77•Produces hydroxide ions (Produces hydroxide ions (OHOH--) in ) in

solutionsolution•Bitter tasteBitter taste•Strong bases can be corrosive.Strong bases can be corrosive.•Look at page 769.Look at page 769.•What do all of the bases have in What do all of the bases have in

common?common?

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Strength of Acids & Strength of Acids & BasesBases

AcidsStrong:Strong: Ionize

Completely in

Solutions.

BasesStrong:Strong: Ionize

Completely in

Solutions.

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NeutralizationNeutralizationACID + Base ==> SALT + WATER

HCl(aq) + NaOH(aq)==> NaCl(aq) + HCl(aq) + NaOH(aq)==> NaCl(aq) + HH22O(l)O(l)

H+ ions react with the OHH+ ions react with the OH-- to to produce water.produce water.

A A saltssalts forms from the forms from the negative ionnegative ion in the acid and the in the acid and the positive ionpositive ion in the in the base.base.ACID + ALKALI ==> SALT + WATER

HCl(aq) + Ca(OH)2(aq)==> CaCl2(aq) + H2O(l)

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Litmus Paper / Litmus Paper / pH paperpH paper

Testing pH

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Litmus paper contains a substance that changes color in either an acid or a base.

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Red Litmus Paper

If red turns blue, it is a BASE!

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Blue Litmus Paper

If blue turns red, it is an ACID!

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Litmus Paper13

Acids & Bases Video

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