CHEM 121 Acid - Bases PPT.pptx - Chapter 9 Acids and Bases 1 Learning Objectives \u2022 \u2022 \u2022 \u2022 \u2022 Identify acids and bases and describe their

CHEM 121 Acid - Bases PPT.pptx - Chapter 9 Acids and Bases...

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Chapter 9Acids and Bases1
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Learning ObjectivesIdentify acids and bases and describe their characteristicsWrite equations for acid-base reactionsAcids and bases strength and effect on the reactionsDefine the acid dissociation K and its relation to acid strengthDefine the concept of the ion-product of water
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Learning ObjectivesCalculate pHDetermine whether a salt solution is acidic, basic or neutralTitration of an acid or baseDescribe the basic principles of a bufferUnderstand the importance of a buffers in maintaining pH in the body3
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4Acids & BasesAcidsSour tasteReact with “active” metalsZn + 2 HCl ZnCl2+ H2React with carbonates, producing CO2CaCO3+ 2 HCl CaCl2+ CO2+ H2OReact with bases to form ionic salts BasesKnown As Alkalis,Taste bitter, Feel slipperyReact with acids to form ionic salts
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5Introduction to Acids and BasesThe earliest definition was given by Arrhenius:An acid contains a hydrogen atom and dissolvesin water to form a hydrogen ion, H+.A base contains hydroxide and dissolves in waterto form OH.HCl(g)acidH+(aq) + Cl(aq) NaOH(s)baseNa+(aq) + OH(aq)
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6Introduction to Acids and BasesThe Arrhenius definition correctly predicts the behavior of many acids and bases.However, this definition is limited and sometimesinaccurate.For example, H+does not exist in water. Instead, it reacts with water to form the hydronium ion, H3O+.H3O+(aq) H+(aq) + H2O(l) hydrogen ion:does not really exist in solutionhydronium ion:actually present inaqueous solution
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7Introduction to Acids and BasesThe Brønsted–Lowry definition is more widely used:A Brønsted–Lowry acid is a proton (H+) donor. A Brønsted–Lowry base is a proton (H+) acceptor.H3O+(aq) + Cl(aq)HCl(g) + H2O(l)This proton is donated.HCl is a Brønsted–Lowry acid because it donatesa proton to the solvent water.H2O is a Brønsted–Lowry base because it acceptsa proton from HCl.
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8According to the Brønsted-Lowry theory,Acids are hydrogen ion (H+) donors. Bases are hydrogen ion (H+) acceptors.donor acceptor hydronium ionHCl + H2O H3O++ Cl-+ -++Bronsted-Lowry Acids and Bases
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9When NH3dissolves in water, a few NH3molecules react with water to form ammonium ion NH4+and a hydroxide ion.NH3+ H2O NH4+(aq) + OH-(aq)acceptor donor+-++NH3, A Bronsted-Lowry Base
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10Introduction to Acids and BasesBrønsted–Lowry AcidsA Brønsted–Lowry acid must contain a hydrogen atom.Common Brønsted–Lowry acids (HA): HClhydrochloric acidHBrhydrobromic acidCHHHCOOHacidic H atomacetic acidH2SO4sulfuric acidHNO3nitric acid
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11Introduction to Acids and BasesBrønsted–Lowry AcidsA monoprotic acid contains one acidic proton.
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