Ch_322a_3.03

Ch_322a_3.03 - + H 2 O fast HO-+ H-B chemical species in...

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Acid-Base Reactions The Bronsted-Lowry Definitions In 1923 the Danish chemist Johannes Bronsted (1879-1947) and the English chemist Thomas Lowry (1874-1936) independently proposed that acids and bases be defined in terms of their ability to give up or accept a proton . H-O H : : H -Cl + base acid (accepts H + ) (gives up H + ) H-O- H H + + Cl : : : - conjugate acid of H 2 O conjugate base of HCl
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Conjugate Pairs The species formed when an acid loses a proton is the conjugate base . The species formed when a base accepts a proton is the conjugate acid . Conjugate pairs are pairs of chemical species that only differ in H + such as H 2 O/H 3 O + HCl/Cl - Diprotic Acids Diprotic acids have two acidic protons that may be released. An example is sulfuric acid where the two H + are sequentially released. (1) H 2 SO 4 + H 2 O H 3 O + + HSO 4 - (2) HSO 4 - + H 2 O H 3 O + + SO 4 2- Step 1 occurs completely while step 2 proceeds to only about 10% in water.
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The Leveling Effect of Water H -A very strong acid + H 2 O H 3 O + + A - fast B: - very strong base
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Unformatted text preview: + H 2 O fast HO-+ H-B chemical species in water A practical consequence of the leveling effect of water is that most organic reactions that involve very strong bases or acids are carried out in nonaqueous solvents such as ethers or hydrocarbons. The "leveling effect of water" refers to the limitations imposed on acid and base strengths in water because of the acid-base reactions of water. The strongest acids and bases that can exist in water are H 3 O + and HO-. When stronger acids or bases are added to water, they immediately react with water to produce these species. Quiz 3.03 In the reaction below, identify the acid , base , conjugate acid and conjugate base . CH 3 C CH + NaNH 2 CH 3 C CNa + NH 3 Solution Use the Bronsted-Lowry definitions. Look for the species that give up and accept the proton. acid base conjugate base conjugate acid...
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This note was uploaded on 07/22/2009 for the course CHEM 322AL taught by Professor Jung during the Summer '07 term at USC.

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Ch_322a_3.03 - + H 2 O fast HO-+ H-B chemical species in...

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