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Acids and Bases

Acids and Bases
Chapter 14 Acids and BasesTypes of Electrolytes • Salts are watersoluble ionic compounds. All strong electrolytes. +1 • Acids form H ions in water solution. +1 • Bases combine with H ions in water solution. 1 Increases the OH concentration. 1 +1 May either directly release OH or pull H off H O. 2 www.ThesisScientist.comProperties of Acids • Sour taste. • React with ―active‖ metals.  I.e., Al, Zn, Fe, but not Cu, Ag or Au. 2 Al + 6 HCl AlCl + 3 H 3 2  Corrosive. • React with carbonates, producing CO . 2  Marble, baking soda, chalk, limestone. CaCO + 2 HCl CaCl + CO + H O 3 2 2 2 • Change color of vegetable dyes.  Blue litmus turns red. • React with bases to form ionic salts. www.ThesisScientist.comCommon Acids Chemical name Formula Uses Strength Explosive, fertilizer, dye, glue Nitric acid HNO Strong 3 Explosive, fertilizer, dye, glue, Sulfuric acid H SO Strong 2 4 batteries Metal cleaning, food prep, ore Hydrochloric acid HCl Strong refining, stomach acid Fertilizer, plastics and rubber, Phosphoric acid H PO Moderate 3 4 food preservation Plastics and rubber, food Acetic acid HC H O Weak 2 3 2 preservation, vinegar Metal cleaning, glass etching Hydrofluoric acid HF Weak Soda water Carbonic acid H CO Weak 2 3 Eye wash Boric acid H BO Weak 3 3 www.ThesisScientist.comStructures of Acids • Binary acids have acid hydrogens attached to a nonmetal atom. HCl, HF Hydrofluoric acid www.ThesisScientist.comStructure of Acids • Oxyacids have acid hydrogens attached to an oxygen atom. H SO , HNO 2 4 3 www.ThesisScientist.comStructure of Acids • Carboxylic acids have COOH group.  HC H O , H C H O 2 3 2 3 6 5 3 • Only the first H in the formula is acidic.  The H is on the COOH. www.ThesisScientist.comProperties of Bases • Also known as alkalis. • Taste bitter.  Alkaloids = Plant product that is alkaline. Often poisonous. • Solutions feel slippery. • Change color of vegetable dyes.  Different color than acid.  Red litmus turns blue. • React with acids to form ionic salts.  Neutralization. www.ThesisScientist.comCommon Bases Chemical Common Formula Uses Strength name name Sodium Lye, Soap, plastic, NaOH Strong hydroxide caustic soda petrol refining Potassium Caustic Soap, cotton, KOH Strong hydroxide potash electroplating Calcium Ca(OH) Slaked lime Cement Strong 2 hydroxide Sodium NaHCO Baking soda Cooking, antacid Weak 3 bicarbonate Magnesium Milk of Mg(OH) Antacid Weak 2 hydroxide magnesia Detergent, Ammonium NH OH, Ammonia 4 fertilizer, Weak hydroxide NH (aq) water 3 explosives, fibers www.ThesisScientist.comStructure of Bases • Most ionic bases contain OH ions.  NaOH, Ca(OH) 2 2 • Some contain CO ions. 3  CaCO NaHCO 3 3 • Molecular bases contain structures that react with + H .  Mostly amine groups. www.ThesisScientist.comArrhenius Theory • Bases dissociate in water to produce OH ions and cations.  Ionic substances dissociate in water. + – NaOH(aq) → Na (aq) + OH (aq) + • Acids ionize in water to produce H ions and anions.  Because molecular acids are not made of ions, they cannot dissociate.  They must be pulled apart, or ionized, by the water. + – HCl(aq) → H (aq) + Cl (aq)  In formula, ionizable H is written in front. + – HC H O (aq) → H (aq) + C H O (aq) 2 3 2 2 3 2 www.ThesisScientist.comArrow Conventions • Chemists commonly use two kinds of arrows in reactions to indicate the degree of completion of the reactions. • A single arrow indicates that all the reactant molecules are converted to product molecules at the end. • A double arrow indicates that the reaction stops when only some of the reactant molecules have been converted into products.  in these notes. www.ThesisScientist.comArrhenius Theory, Continued HCl ionizes in water, NaOH dissociates in water, + – + – producing H and Cl ions. producing Na and OH ions. www.ThesisScientist.comBrønsted–Lowry Theory • A BrønstedLowry acid–base reaction is any + reaction in which an H is transferred.  Does not have to take place in aqueous solution.  Broader definition than Arrhenius. + + • Acid is H donor; base is H acceptor. +  Since H is a proton, acid is a proton donor and base is a proton acceptor.  Base structure must contain an atom with an + unshared pair of electrons to bond to H . + • In the reaction, the acid molecule gives an H to the base molecule. – + H–A + :B  :A + H–B www.ThesisScientist.comComparing Arrhenius Theory and Brønsted–Lowry Theory • Brønsted–Lowry theory • Arrhenius theory HCl(aq) + H O(l)  HCl(aq)  2 − + + − Cl (aq) + H O (aq) H (aq) + Cl (aq) 3 HF(aq) + H O(l)  HF(aq)  2 + − − + H (aq) + F (aq) F (aq) + H O (aq) 3 NaOH(aq)  NaOH(aq) + H O(l)  2 + − + − Na (aq) + OH (aq) Na (aq) + OH (aq) + H O(l) 2 NH OH(aq)  NH (aq) + H O(l)  4 3 2 + − + − NH (aq) + OH (aq) NH (aq) + OH (aq) 4 4 www.ThesisScientist.comAmphoteric Substances • Amphoteric substances can act as either an acid or a base.  They have both transferable H and an atom with a lone pair. + • HCl(aq) is acidic because HCl transfers an H to + H O, forming H O ions. 2 3 +  Water acts as base, accepting H . – + HCl(aq) + H O(l) → Cl (aq) + H O (aq) 2 3 + • NH (aq) is basic because NH accepts an H from 3 3 – H O, forming OH (aq). 2 +  Water acts as acid, donating H . + – NH (aq) + H O(l)  NH (aq) + OH (aq) 3 2 4 www.ThesisScientist.comConjugate Pairs • In a BrønstedLowry acidbase reaction, the original base becomes an acid in the reverse reaction, and the original acid becomes a base in the reverse process. • Each reactant and the product it becomes is called a conjugate pair. • The original base becomes the conjugate acid; the original acid becomes the conjugate base. www.ThesisScientist.comExample—Identify the Brønsted–Lowry Acids and Bases and Their Conjugates in the Reaction. – + H SO + H O HSO + H O 2 4 2 4 3  + When the H SO becomes HSO , it loses an H , so 2 4 4  H SO must be the acid and HSO its conjugate base. 2 4 4 + + When the H O becomes H O , it accepts an H , so 2 3 + H O must be the base and H O its conjugate acid. 2 3 – + H SO + H O HSO + H O 2 4 2 4 3 Acid Base Conjugate Conjugate base acid www.ThesisScientist.comExample—Identify the BrønstedLowry Acids and Bases and Their Conjugates in the Reaction, Continued. – – HCO + H O H CO + HO 3 2 2 3 +  When the HCO becomes H CO , it accepts an H , so 3 2 3  HCO must be the base and H CO its conjugate acid. 3 2 3  + When the H O becomes OH , it donates an H , so 2  H O must be the acid and OH its conjugate base. 2 – – HCO + H O H CO + HO 3 2 2 3 Base Acid Conjugate Conjugate acid base www.ThesisScientist.comPractice—Write the Formula for the Conjugate Acid of the Following: + •H O H O 2 3 + •NH NH 3 4 2− − •CO HCO 3 3 1− •H PO H PO 2 4 3 4 www.ThesisScientist.comPractice—Write the Formula for the Conjugate Base of the Following: − •H O HO 2 − •NH NH 3 2 2− 2− •CO Since CO does not have an H, it cannot be an acid. 3 3 2− HPO 1− 4 •H PO 2 4 www.ThesisScientist.comPractice—Write the Equations for the Following Reacting with Water and Acting as a Monoprotic Acid. Label the Conjugate Acid and Base. 1 2 +1 1 HSO + H O  SO + H O HSO 4 2 4 3 4 Acid Base Conjugate Conjugate base acid 2− − − CO + H O  HCO + OH 3 2 3 2− CO 3 Base Acid Conjugate Conjugate acid base www.ThesisScientist.comNeutralization Reactions + • H + OH H O 2 • Acid + base salt + water • Doubledisplacement reactions.  Salt = cation from base + anion from acid.  Cation and anion charges stay constant. H SO + Ca(OH) → CaSO + 2 H O 2 4 2 4 2 • Some neutralization reactions are gas evolving, where H CO decomposes 2 3 into CO and H O. 2 2 H SO + 2 NaHCO → Na SO + 2 H O + 2 CO 2 4 3 2 4 2 2 www.ThesisScientist.comPractice–Complete Each Reaction. • Ca(OH) (s) + H SO (aq)  2 2 3 • HClO (aq) + Pb(OH) (s)  3 4 • CaCO (s) + HNO (aq) 3 3 • Mg(HCO ) (aq) + HC H O (aq) 3 2 2 3 2 www.ThesisScientist.comPractice–Complete Each Reaction, Continued. • Ca(OH) (s) + H SO (aq)  CaSO (s) + 2 H O(l) 2 2 3 3 2 • 4 HClO (aq) + Pb(OH) (s)  Pb(ClO ) (s) + 4 H O(l) 3 4 3 4 2 • CaCO (s) + 2 HNO (aq) Ca(NO ) (aq) + CO (g) + 2 H O(l) 3 3 3 2 2 2 • Mg(HCO ) (aq) + 2 HC H O (aq) Mg(C H O ) (aq) + 2 CO (g) + 2 H O(l) 3 2 2 3 2 2 3 2 2 2 2 www.ThesisScientist.comAcid Reactions: Acids React with Metals • Acids react with many metals. But not all • When acids react with metals, they produce a salt and hydrogen gas. 3 H SO (aq) + 2 Al(s) → Al (SO ) (aq) + 3 H (g) 2 4 2 4 3 2 www.ThesisScientist.comTitration • Titration is a technique that uses reaction stoichiometry to determine the concentration of an unknown solution. • Titrant (unknown solution) is added from a buret. • Indicators are chemicals that are added to help determine when a reaction is complete. • The endpoint of the titration occurs when the reaction is complete. www.ThesisScientist.comTitration, Continued www.ThesisScientist.comAcid–Base Titration The base solution is the titrant in the buret. As the base is added to + the acid, the H reacts with – the OH to form water. But there is still excess acid present, so the color does not change. At the titration’s endpoint, just enough base has been added to neutralize all the acid. At this point, the indicator changes color: – H+ = OH www.ThesisScientist.comExample 14.4—What Is the Molarity of an HCl Solution if 10.00 mL Is required to Titrate 12.54 mL of 0.100 M NaOH NaOH(aq) + HCl(aq)  NaCl(aq) + H O(l) 2 Given: 12.54 mL NaOH, 10.00 mL HCl Find: M HCl mol Solution Map: M mL L NaOH mol NaOH mol HCl L M mL HCl L HCl M = mol/L, 1 mol NaOH = 1 mol HCl, 1 mL = 0.001L Relationships: Solve: 3 0.001 L 0.100 mol NaOH 1 mol HCl 1.254 10 mol HCl 3 12.54 mL NaOH1.25410 mol HCl M 2 1 mL 1 L 1 mol NaOH 1.00010 L HCl 0.001 L 2 M  0.125 M HCl 10.00 mL HCl 1.00010 L HCl 1 mL Check: The unit is correct, the magnitude is reasonable. www.ThesisScientist.comPractice—What Is the Molarity of a Ba(OH) Solution if 2 37.6 mL Is Required to Titrate 43.8 mL of 0.107 M HCl Ba(OH) (aq) + 2 HCl(aq)  BaCl (aq) + 2 H O(l) 2 2 2 www.ThesisScientist.comPractice—What Is the Molarity of a Ba(OH) Solution if 37.6 mL 2 Is Required to Titrate 43.8 mL of 0.107 M HCl Ba(OH) (aq) + 2 HCl(aq)  BaCl (aq) + 2 H O(l), Continued 2 2 2 Given: 37.6 mL Ba(OH) , 43.8 mL HCl 2 Find: M Ba(OH) 2 mol Solution Map: M mL L HCl mol HCl mol Ba(OH) 2 L M mL Ba(OH) L Ba(OH) 2 2 Relationships: M = mol/L, 1 mol Ba(OH) = 2 mol HCl, 1 mL = 0.001L 2 3 Solve: 2.343 10 mol Ba(OH) 2 0.001 L 0.107 mol HCl 1 mol Ba(OH) 3 2 M 43.8 mL HCl 2.34310 mol Ba(OH) 2 2 1 mL 1 L 2 mol HCl 3.7610 mol Ba(OH) 2 0.001 L 2 37.6 mL Ba(OH)  3.7610 L Ba(OH) M  0.0623 M Ba(OH) 2 2 2 1 mL Check: The unit is correct, the magnitude is reasonable. www.ThesisScientist.comStrong Acids • The stronger the acid, the + HCl  H + Cl more willing it is to donate H. + HCl + H O H O + Cl  Use water as the standard base. 2 3 • Strong acids donate practically all their Hs.  100 ionized in water.  Strong electrolyte. + • H O = strong acid. 3  = molarity. www.ThesisScientist.comStrong Acids, Continued Hydrochloric acid HCl Hydrobromic acid HBr Hydroiodic acid HI Nitric acid HNO 3 Perchloric acid HClO 4 Sulfuric acid H SO 2 4 www.ThesisScientist.comStrong Acids, Continued Pure water HCl solution www.ThesisScientist.comWeak Acids • Weak acids donate a small + HF  H + F + fraction of their Hs. HF + H O  H O + F 2 3 Most of the weak acid molecules do not donate H to water. Much less than 1 ionized in water. + • H O weak acid. 3 www.ThesisScientist.comWeak Acids, Continued Hydrofluoric acid HF Acetic acid HC H O 2 3 2 Formic acid HCHO 2 Sulfurous acid H SO 2 3 Carbonic acid H CO 2 3 Phosphoric acid H PO 3 4 www.ThesisScientist.comWeak Acids, Continued Pure water HF solution www.ThesisScientist.comDegree of Ionization • The extent to which an acid ionizes in water depends in part on the strength of the bond + between the acid H and anion compared to + the strength of the bond between the acid H and the O of water. − + HA(aq) + H O(l)  A (aq) + H O (aq) 2 3 www.ThesisScientist.comRelationship Between Strengths of Acids and Their Conjugate Bases • The stronger an acid is, the weaker the attraction of the ionizable H for the rest of the molecule is. • The better the acid is at donating H, the worse its conjugate base will be at accepting an H. – + Strong acid HCl + H O → Cl + H O Weak conjugate base 2 3 – + Weak acid HF + H O  F + H O Strong conjugate base 2 3 www.ThesisScientist.comStrong Bases • The stronger the base, the more + NaOH  Na + OH willing it is to accept H.  Use water as the standard acid. • Strong bases, practically all molecules are dissociated into – OH or accept Hs.  Strong electrolyte.  MultiOH bases completely dissociated. – • HO = strong base x ( OH). www.ThesisScientist.comStrong Bases, Continued Lithium hydroxide LiOH Sodium hydroxide NaOH Potassium hydroxide KOH Calcium hydroxide Ca(OH) 2 Strontium hydroxide Sr(OH) 2 Barium hydroxide Ca(OH) 2 www.ThesisScientist.comWeak Bases • In weak bases, only a small + NH + H O  NH + OH 3 2 4 fraction of molecules accept Hs.  Weak electrolyte.  Most of the weak base molecules do not take H from water.  Much less than 1 ionization in water. – • HO strong base. www.ThesisScientist.comAutoionization of Water • Water is actually an extremely weak electrolyte.  Therefore, there must be a few ions present. • About 1 out of every 10 million water molecules form ions through a process called autoionization. + – H O  H + OH 2 + – H O + H O  H O + OH 2 2 3 + – • All aqueous solutions contain both H O and OH . 3 + –  The concentration of H O and OH are equal in water. 3 + – 7  H O = OH = 1 x 10 M at 25 °C in pure water. 3 www.ThesisScientist.comIon Product of Water + – • The product of the H O and OH 3 concentrations is always the same number. • The number is called the ion product of water and has the symbol K . w + – 14 • H O x OH = 1 x 10 = K . 3 w + – • As H O increases, the OH must 3 decrease so the product stays constant. Inversely proportional. www.ThesisScientist.comAcidic and Basic Solutions + – • Neutral solutions have equal H O and OH . 3 + – 7 H O = OH = 1 x 10 3 + – • Acidic solutions have a larger H O than OH . 3 + 7 – 7 H O 1 x 10 ; OH 1 x 10 3 – + • Basic solutions have a larger OH than H O . 3 + 7 – 7 H O 1 x 10 ; OH 1 x 10 3 www.ThesisScientist.com+ Example—Determine the H O for a 0.00020 M 3 Ba(OH) and Determine Whether the Solution Is 2 Acidic, Basic, or Neutral. 2+ – Ba(OH) = Ba + 2 OH therefore: 2 – −4 OH = 2 x 0.00020 = 0.00040 = 4.0 x 10 M   H O K OH 3 w 14 K110  w H O  3  4 4.010 OH + 11 H O = 2.5 x 10 M. 3 + −7 Since H O 1 x 10 , the solution is basic. 3 www.ThesisScientist.com+ Practice—Determine the H O 3 Concentration and Whether the Solution Is Acidic, Basic, or Neutral for the Following: – • OH = 0.000250 M – 8 • OH = 3.50 x 10 M • Ca(OH) = 0.20 M 2 www.ThesisScientist.com+ Practice—Determine the H O Concentration 3 and Whether the Solution Is Acidic, Basic, or Neutral for the Following, Continued: – • OH = 0.000250 M 14 1 x 10 + 1 + 11 H O OH , therefore, base. H O = = 4.00 x 10 3 3 4 2.50 x 10 – 8 • OH = 3.50 x 10 M 14 1 x 10 + 1 + 7 H O OH , therefore, acid. H O = = 2.86 x 10 3 3 8 3.50 x 10 1 OH = 2 x 0.20 = 0.40 M • Ca(OH) = 0.20 M 2 14 1 x 10 + 1 + 14 H O OH , therefore, H O = = 2.5 x 10 3 3 1 4.0 x 10 base. www.ThesisScientist.comComplete the Table + H vs. OH + 0 1 3 5 7 9 11 13 14 H 10 10 10 10 10 10 10 10 10 + H + H + H + + H H OH OH OH OH OH OH www.ThesisScientist.compH • The acidity/basicity of a solution is often expressed as pH. + + −pH • pH = ─logH O , H O = 10 3 3  Exponent on 10 with a positive sign. 7  pH = −log10 = 7. water +  Need to know the H concentration to find pH. • pH 7 is acidic; pH 7 is basic; pH = 7 is neutral. www.ThesisScientist.compH, Continued • The lower the pH, the more acidic the solution; the higher the pH, the more basic the solution. 1 pH unit corresponds to a factor of 10 difference in acidity. • Normal range is 0 to 14. + – pH 0 is H = 1 M, pH 14 is OH = 1 M. pH can be negative (very acidic) or larger than 14 (very alkaline). www.ThesisScientist.compH of Common Substances Substance pH 1.0 M HCl 0.0 0.1 M HCl 1.0 Stomach acid 1.0 to 3.0 Lemons 2.2 to 2.4 Soft drinks 2.0 to 4.0 Plums 2.8 to 3.0 Apples 2.9 to 3.3 Cherries 3.2 to 4.0 Unpolluted rainwater 5.6 Human blood 7.3 to 7.4 Egg whites 7.6 to 8.0 Milk of magnesia (saturated Mg(OH) ) 10.5 2 Household ammonia 10.5 to 11.5 www.ThesisScientist.com 1.0 M NaOH 14Example—Calculate the pH of a 0.0010 M Ba(OH) Solution and Determine if It Is 2 Acidic, Basic, or Neutral. 2+ − Ba(OH) = Ba + 2 OH therefore, 2 3 OH = 2 x 0.0010 = 0.0020 = 2.0 x 10 M. 14 1 x 10 + 12 H O = = 5.0 x 10 M 3 3 2.0 x 10 + 12 pH = −log H O = −log (5.0 x 10 ) 3 pH = 11.3 pH 7 therefore, basic. www.ThesisScientist.comPractice—Calculate the pH of the Following Strong Acid or Base Solutions. • 0.0020 M HCl • 0.0050 M Ca(OH) 2 • 0.25 M HNO 3 www.ThesisScientist.comPractice—Calculate the pH of the Following Strong Acid or Base Solutions, Continued. + • 0.0020 M HCl therefore, H O = 0.0020 M. 3 3 pH = −log (2.0 x 10 ) = 2.70 – • 0.0050 M Ca(OH) therefore, OH = 0.010 M. 2 14 − 1 x 10 + −12 H O = = 1.0 x 10 3 2 − 1 x 10 −12 pH = −log (1.0 x 10 ) = 12.00 + • 0.25 M HNO therefore, H O = 0.25 M. 3 3 −1 pH = −log (2.5 x 10 ) = 0.60 www.ThesisScientist.comExample—Calculate the Concentration + of H O for a Solution with pH 3.7. 3 + pH H O = 10 3 + 3.7 H O = 10 3 +1 means 0.0001 H 0.001. + 4 H O = 2 x 10 M = 0.0002 M. 3 www.ThesisScientist.com+ Practice—Determine the H O for 3 Each of the Following: • pH = 2.7 • pH = 12 • pH = 0.60 www.ThesisScientist.com+ Practice—Determine the H O for 3 Each of the Following, Continued: • pH = 2.7 + −2.7 −3 H O = 10 = 2 x 10 M = 0.002 M 3 • pH = 12 + −12 12 H O = 10 = 1 x 10 M 3 • pH = 0.60 + −0.60 H O = 10 = 0.25 M 3 www.ThesisScientist.compOH • The acidity/basicity of a solution may also be expressed as pOH. − − −pOH • pOH = ─logOH , OH = 10 Exponent on 10 with a positive sign. −7 pOH = −log10 = 7. water − Need to know the OH concentration to find pOH. • pOH 7 is acidic; pOH 7 is basic, pOH = 7 is neutral. www.ThesisScientist.compOH, Continued • The lower the pOH, the more basic the solution; the higher the pOH, the more acidic the solution. 1 pOH unit corresponds to a factor of 10 difference in basicity. • Normal range is 0 to 14. − + pOH 0 is OH = 1 M; pOH 14 is H O = 1 M. 3 pOH can be negative (very basic) or larger than 14 (very acidic). • pH + pOH = 14.00. www.ThesisScientist.comExample—Calculate the pH of a 0.0010 M Ba(OH) Solution and Determine if It Is 2 Acidic, Basic, or Neutral. +2 − Ba(OH) = Ba + 2 OH therefore, 2 − −3 OH = 2 x 0.0010 = 0.0020 = 2.0 x 10 M. − −3 pOH = log OH = log (2.0 x 10 ) pOH = 2.70 pH = 14.00 pOH = 14.00 2.70 pH = 11.30 pH 7 therefore, basic. www.ThesisScientist.comPractice—Calculate the pOH and pH of the Following Strong Acid or Base Solutions. • 0.0020 M KOH • 0.0050 M Ca(OH) 2 • 0.25 M HNO 3 www.ThesisScientist.comPractice—Calculate the pOH and pH of the Following Strong Acid or Base Solutions, Continued. – • 0.0020 M KOH therefore, OH = 0.0020 M. 3 pOH = −log (2.0 x 10 ) = 2.70 pH = 14.00 – 2.70 = 11.30 – • 0.0050 M Ca(OH) therefore, OH = 0.010 M. 2 2 pOH = −log (1.0 x 10 ) = 2.00 pH = 14.00 – 2.00 = 12.00 + • 0.25 M HNO therefore, H O = 0.25 M. 3 3 1 pH = −log (2.5 x 10 ) = 0.60 pOH = 14.00 – 0.60 = 13.40 www.ThesisScientist.comBuffers • Buffers are solutions that resist changing pH when small amounts of acid or base are added. • They resist changing pH by neutralizing added acid or base. • Buffers are made by mixing together a weak acid and its conjugate base. Or weak base and its conjugate acid. www.ThesisScientist.comHow Buffers Work • The weak acid present in the buffer mixture can neutralize added base. • The conjugate base present in the buffer mixture can neutralize added acid. • The net result is little to no change in the solution pH. www.ThesisScientist.comHow Buffers Work, Continued H O 2 New HA + − HA H O  − HA A 3 + A Added + H O 3 www.ThesisScientist.comHow Buffers Work, Continued H O New 2 − A + − HA H O  − A 3 + HA A Added − HO www.ThesisScientist.comA Buffer Made from Acetic Acid and Sodium Acetate • A buffer solution with a pH of 4.75 can be made by mixing equal volumes of 1 M HC H O and 1 M 2 3 2 NaC H O . 2 3 2 • Adding 10 mL of 0.1 M HCl to 1 L of this solution will give a solution with a pH of 4.75.  Adding 10 mL of 0.1 M HCl to 1 L of distilled water will give a solution with pH of 3.0. • Adding 10 mL of 0.1 M NaOH to 1 L of this solution will give a solution with a pH of 4.75.  Adding 10 mL of 0.1 M NaOH to 1 L of distilled water will give a solution with pH of 11.0. www.ThesisScientist.comAcetic Acid/Acetate Buffer www.ThesisScientist.comNonmetal Oxides Are Acidic • Nonmetal oxides react with water to form acids. • Causes acid rain. CO (g) + H O(l) → H CO (aq) 2 2 2 3 2 SO (g) + O (g) + 2 H O(l) → 2 H SO (aq) 2 2 2 2 4 4 NO (g) + O (g) + 2 H O(l) → 4 HNO (aq) 2 2 2 3 www.ThesisScientist.comWhat Is Acid Rain • Natural rain water has a pH of 5.6. Naturally slightly acidic due mainly to CO . 2 • Rain water with a pH lower than 5.6 is called acid rain. • Acid rain is linked to damage in ecosystems and structures. www.ThesisScientist.comWhat Causes Acid Rain • Many natural and pollutant gases dissolved in the air are nonmetal oxides.  CO , SO , NO . 2 2 2 • Nonmetal oxides are acidic. CO + H O  H CO 2 2 2 3 2 SO + O + 2 H O  2 H SO 2 2 2 2 4 • Processes that produce nonmetal oxide gases as waste increase the acidity of the rain.  Natural—volcanoes and some bacterial action.  Manmade—combustion of fuel. • Weather patterns may cause rain to be acidic in regions other than where the nonmetal oxide is produced. www.ThesisScientist.compH of Rain in Different Regions www.ThesisScientist.comSources of SO from Utilities 2 www.ThesisScientist.comDamage from Acid Rain • Acids react with metals and materials that contain carbonates. • Acid rain damages bridges, cars, and other metallic structures. • Acid rain damages buildings and other structures made of limestone or cement. • Acidifies lakes affecting aquatic life. • Dissolves and leaches more minerals from soil.  Making it difficult for trees. www.ThesisScientist.comDamage from Acid Rain circa 1995 circa 1935 www.ThesisScientist.compH of Rain in Different Regions www.ThesisScientist.comSources of SO from Utilities 2 www.ThesisScientist.comAcid Rain Legislation • 1990 Clean Air Act attacks acid rain. Forces utilities to reduce SO . 2 • The result is acid rain in the northeast is stabilized and begins to be reduced. www.ThesisScientist.com
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