Conjugate Acid Base Pairs • Conjugate Base: Formed from an Acid When It Donates a Proton to a Base
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The Strongest Acid Christopher A
Chemistry in New Zealand October 2011 The Strongest Acid Christopher A. Reed Department of Chemistry, University of California, Riverside, California 92521, USA Article (e-mail: [email protected]) About the Author Chris Reed was born a kiwi to English parents in Auckland in 1947. He attended Dilworth School from 1956 to 1964 where his interest in chemistry was un- doubtedly stimulated by being entrusted with a key to the high school chemical stockroom. Nighttime experiments with white phosphorus led to the Headmaster administering six of the best. He obtained his BSc (1967), MSc (1st Class Hons., 1968) and PhD (1971) from The University of Auckland, doing thesis research on iridium organotransition metal chemistry with Professor Warren R. Roper FRS. This was followed by two years of postdoctoral study at Stanford Univer- sity with Professor James P. Collman working on picket fence porphyrin models for haemoglobin. In 1973 he joined the faculty of the University of Southern California, becoming Professor in 1979. After 25 years at USC, he moved to his present position of Distinguished Professor of Chemistry at UC-Riverside to build the Centre for s and p Block Chemistry. His present research interests focus on weakly coordinating anions, weakly coordinated ligands, acids, si- lylium ion chemistry, cationic catalysis and reactive cations across the periodic table. His earlier work included extensive studies in metalloporphyrin chemistry, models for dioxygen-binding copper proteins, spin-spin coupling phenomena including paramagnetic metal to ligand radical coupling, a Magnetochemi- cal alternative to the Spectrochemical Series, fullerene redox chemistry, fullerene-porphyrin supramolecular chemistry and metal-organic framework solids (MOFs). -
A Guide to Acids, Acid Strength, and Concentration
A GUIDE TO ACIDS, ACID STRENGTH, AND CONCENTRATION What’s the difference between acid strength and concentration? And how does pH fit in with these? This graphic explains the basics. CH COOH HCl H2SO4 HNO3 H3PO4 HF 3 H2CO3 HYDROCHLORIC ACID SULFURIC ACID NITRIC ACID PHOSPHORIC ACID HYDROFLUORIC ACID ETHANOIC ACID CARBONIC ACID pKa = –7 pKa = –2 pKa = –2 pKa = 2.12 pKa = 3.45 pKa = 4.76 pKa = 6.37 STRONGER ACIDS WEAKER ACIDS STRONG ACIDS VS. WEAK ACIDS ACIDS, Ka AND pKa CONCENTRATION AND pH + – The H+ ion is transferred to a + A decrease of one on the pH scale represents + [H+] [A–] pH = –log10[H ] a tenfold increase in H+ concentration. HA H + A water molecule, forming H3O Ka = pKa = –log10[Ka] – [HA] – – + + A + + A– + A + A H + H H H H A H + H H H A Ka pK H – + – H a A H A A – + A– A + H A– H A– VERY STRONG ACID >0.1 <1 A– + H A + + + – H H A H A H H H + A – + – H A– A H A A– –3 FAIRLY STRONG ACID 10 –0.1 1–3 – – + A A + H – – + – H + H A A H A A A H H + A A– + H A– H H WEAK ACID 10–5–10–3 3–5 STRONG ACID WEAK ACID VERY WEAK ACID 10–15–10–5 5–15 CONCENTRATED ACID DILUTE ACID + – H Hydrogen ions A Negative ions H A Acid molecules EXTREMELY WEAK ACID <10–15 >15 H+ Hydrogen ions A– Negative ions Acids react with water when they are added to it, The acid dissociation constant, Ka, is a measure of the Concentration is distinct from strength. -
Acids Lewis Acids and Bases Lewis Acids Lewis Acids: H+ Cu2+ Al3+ Lewis Bases
E5 Lewis Acids and Bases (Session 1) Acids November 5 - 11 Session one Bronsted: Acids are proton donors. • Pre-lab (p.151) due • Problem • 1st hour discussion of E4 • Compounds containing cations other than • Lab (Parts 1and 2A) H+ are acids! Session two DEMO • Lab: Parts 2B, 3 and 4 Problem: Some acids do not contain protons Lewis Acids and Bases Example: Al3+ (aq) = ≈ pH 3! Defines acid/base without using the word proton: + H H H • Cl-H + • O Cl- • • •• O H H Acid Base Base Acid . A BASE DONATES unbonded ELECTRON PAIR/S. An ACID ACCEPTS ELECTRON PAIR/S . Deodorants and acid loving plant foods contain aluminum salts Lewis Acids Lewis Bases . Electron rich species; electron pair donors. Electron deficient species ; potential electron pair acceptors. Lewis acids: H+ Cu2+ Al3+ “I’m deficient!” Ammonia hydroxide ion water__ (ammine) (hydroxo) (aquo) Acid 1 Lewis Acid-Base Reactions Lewis Acid-Base Reactions Example Metal ion + BONDED H H H + • to water H + • O O • • •• molecules H H Metal ion Acid + Base Complex ion surrounded by water . The acid reacts with the base by bonding to one molecules or more available electron pairs on the base. The acid-base bond is coordinate covalent. The product is a complex or complex ion Lewis Acid-Base Reaction Products Lewis Acid-Base Reaction Products Net Reaction Examples Net Reaction Examples 2+ 2+ + + Pb + 4 H2O [Pb(H2O)4] H + H2O [H(H2O)] Lewis acid Lewis base Tetra aquo lead ion Lewis acid Lewis base Hydronium ion 2+ 2+ 2+ 2+ Ni + 6 H2O [Ni(H2O)6] Cu + 4 H2O [Cu(H2O)4] Lewis acid Lewis base Hexa aquo nickel ion Lewis acid Lewis base Tetra aquo copper(II)ion DEMO DEMO Metal Aquo Complex Ions Part 1. -
Introduction to Ionic Mechanisms Part I: Fundamentals of Bronsted-Lowry Acid-Base Chemistry
INTRODUCTION TO IONIC MECHANISMS PART I: FUNDAMENTALS OF BRONSTED-LOWRY ACID-BASE CHEMISTRY HYDROGEN ATOMS AND PROTONS IN ORGANIC MOLECULES - A hydrogen atom that has lost its only electron is sometimes referred to as a proton. That is because once the electron is lost, all that remains is the nucleus, which in the case of hydrogen consists of only one proton. The large majority of organic reactions, or transformations, involve breaking old bonds and forming new ones. If a covalent bond is broken heterolytically, the products are ions. In the following example, the bond between carbon and oxygen in the t-butyl alcohol molecule breaks to yield a carbocation and hydroxide ion. H3C CH3 H3C OH H3C + OH CH3 H3C A tertiary Hydroxide carbocation ion The full-headed curved arrow is being used to indicate the movement of an electron pair. In this case, the two electrons that make up the carbon-oxygen bond move towards the oxygen. The bond breaks, leaving the carbon with a positive charge, and the oxygen with a negative charge. In the absence of other factors, it is the difference in electronegativity between the two atoms that drives the direction of electron movement. When pushing arrows, remember that electrons move towards electronegative atoms, or towards areas of electron deficiency (positive, or partial positive charges). The electron pair moves towards the oxygen because it is the more electronegative of the two atoms. If we examine the outcome of heterolytic bond cleavage between oxygen and hydrogen, we see that, once again, oxygen takes the two electrons because it is the more electronegative atom. -
Lesson 21: Acids & Bases
Lesson 21: Acids & Bases - Far From Basic Lesson Objectives: • Students will identify acids and bases by the Lewis, Bronsted-Lowry, and Arrhenius models. • Students will calculate the pH of given solutions. Getting Curious You’ve probably heard of pH before. Many personal hygiene products make claims about pH that are sometimes based on true science, but frequently are not. pH is the measurement of [H+] ion concentration in any solution. Generally, it can tell us about the acidity or alkaline (basicness) of a solution. Click on the CK-12 PLIX Interactive below for an introduction to acids, bases, and pH, and then answer the questions below. Directions: Log into CK-12 as follows: Username - your Whitmore School Username Password - whitmore2018 Questions: Copy and paste questions 1-3 in the Submit Box at the bottom of this page, and answer the questions before going any further in the lesson: 1. After dragging the small white circles (in this simulation, the indicator papers) onto each substance, what do you observe about the pH of each substance? 2. If you were to taste each substance (highly inadvisable in the chemistry laboratory!), how would you imagine they would taste? 3. Of the three substances, which would you characterize as acid? Which as basic? Which as neutral? Use the observed pH levels to support your hypotheses. Chemistry Time Properties of Acids and Bases Acids and bases are versatile and useful materials in many chemical reactions. Some properties that are common to aqueous solutions of acids and bases are listed in the table below. Acids Bases conduct electricity in solution conduct electricity in solution turn blue litmus paper red turn red litmus paper blue have a sour taste have a slippery feeling react with acids to create a neutral react with bases to create a neutral solution solution react with active metals to produce hydrogen gas Note: Litmus paper is a type of treated paper that changes color based on the acidity of the solution it comes in contact with. -
Acids and Bases
self study Most of this is probably background from a prior chemistry course; some near the end is GG325 review Aqueous Inorganic Geochemistry of Natural Waters Three important topics: 1. Acids, bases and the aqueous CO 2 system 2. Behavior of ions in aqueous solution 3. Quantifying aqueous solubility and total dissolved solids (TDS) Pease read Manahan chapter 3 and review chapter 28 (6 th Ed) for next week GG425 Wk2, S2016 Acids and Bases GG425 Wk2, S2016 1 1. Two Types of Acids and Bases: a. Brönstead acids and bases contain H + and OH - HCl ↔ H + + + Cl- (acid) NaOH ↔ Na + + OH - (base). + - water is acid and base simultaneously, H 2O ↔ H + OH . pure water and acid neutral aqueous solutions have equal amounts of H + and OH -. b. Lewis acids and bases Brönstead acids can be thought of as electron deficient ions and bases as electron excessive ions , which provides a different perspective on acidity/basisity that we can extend to other (non protic and non hydroxyl) compounds. We call this the Lewis acid/base concept. GG425 Wk2, S2016 Brönstead acidity: Kw is the equilibrium constant for the dissociation of water. + - H2O ↔ H + OH + - -14 Kw = [H ][OH ] = 10 at 25 EC Kw has a slight temperature dependence: Temp ( EC) Kw 0 10 -14.94 less dissociated 25 10 -14 60 10 -13.02 more dissociated GG425 Wk2, S2016 2 Brönstead acidity: + - H2O ↔ H + OH + - Kw = [H ][OH ] An acid neutral solution always has [H +] = [OH -]. Setting [H +] = x, yields x 2= 10 -14 x = 10 -7 = moles of H + in this solution. -
Characterization of the Acidity of Sio2-Zro2 Mixed Oxides
Characterization of the acidity of SiO2-ZrO2 mixed oxides Citation for published version (APA): Bosman, H. J. M. (1995). Characterization of the acidity of SiO2-ZrO2 mixed oxides. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR436698 DOI: 10.6100/IR436698 Document status and date: Published: 01/01/1995 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. -
Chapter Fourteen Acids and Bases
CHAPTER FOURTEEN ACIDS AND BASES For Review 1. a. Arrhenius acid: produce H+ in water b. Bρrnsted-Lowry acid: proton (H+) donor c. Lewis acid: electron pair acceptor The Lewis definition is most general. The Lewis definition can apply to all Arrhenius and Brρnsted-Lowry acids; H+ has an empty 1s orbital and forms bonds to all bases by accepting a pair of electrons from the base. In addition, the Lewis definition incorporates other reactions not typically considered acid-base reactions, e.g., BF3(g) + NH3(g) → F3B−NH3(s). NH3 is something we usually consider a base and it is a base in this reaction using the Lewis definition; NH3 donates a pair of electrons to form the N−B bond. 2. a. The Ka reaction always refers to an acid reacting with water to produce the conjugate + base of the acid and the hydronium ion (H3O ). For a general weak acid HA, the Ka reaction is: − + − HA(aq) + H2O(l) ⇌ A (aq) + H3O (aq) where A = conjugate base of the acid HA This reaction is often abbreviated as: HA(aq) ⇌ H+(aq) + A−(aq) b. The Ka equilibrium constant is the equilibrium constant for the Ka reaction of some sub- stance. For the general Ka reaction, the Ka expression is: − + + − [A ][H3O ] [H ][A ] Ka = or K = (for the abbreviated Ka reaction) [HA] a [HA] c. The Kb reaction alwlays refers to a base reacting with water to produce the conjugate acid − of the base and the hydroxide ion (OH ). For a general base, B, the Kb reaction is: + − + B(aq) + H2O(l) ⇌ BH (aq) + OH (aq) where BH = conjugate acid of the base B [BH+ ][OH− ] d. -
General Chemistry/Properties and Theories of Acids and Bases 1 General Chemistry/Properties and Theories of Acids and Bases
General Chemistry/Properties and Theories of Acids and Bases 1 General Chemistry/Properties and Theories of Acids and Bases Acid-Base Reaction Theories Acids and bases are everywhere. Some foods contain acid, like the citric acid in lemons and the lactic acid in dairy. Cleaning products like bleach and ammonia are bases. Chemicals that are acidic or basic are an important part of chemistry. Helpful Hint! You may need to refresh your memory on naming acids. Several different theories explain what composes an acid and a base. The first scientific definition of an acid was proposed by the French chemist Antoine Lavoisier in the eighteenth century. He proposed that acids contained oxygen, although he did not know the dual composition of acids such as hydrochloric acid (HCl). Over the years, much more accurate definitions of acids and bases have been created. Arrhenius Theory The Swedish chemist Svante Arrhenius published his theory of acids and bases in 1887. It can be simply explained by these two points: Arrhenius Acids and Bases 1. An acid is a substance which dissociates in water to produce one or more hydrogen ions (H+). 2. A base is a substance which dissociates in water to produce one or more hydroxide ions (OH-). Based on this definition, you can see that Arrhenius acids must be soluble in water. Arrhenius acid-base reactions can be summarized with three generic equations: Svante Arrhenius General Chemistry/Properties and Theories of Acids and Bases 2 An acid will dissociate in water producing hydrogen ions. A base (usually containing a metal) will dissociate in water to product hydroxide ions. -
Acid Mine Drainage Prediction
EPA 530-R-94-036 NTIS PB94-201829 TECHNICAL DOCUMENT ACID MINE DRAINAGE PREDICTION December 1994 U.S. Environmental Protection Agency Office of Solid Waste Special Waste Branch 401 M Street, SW Washington, DC 20460 Acid Mine Drainage Prediction DISCLAIMER AND ACKNOWLEDGEMENTS This document was prepared by the U.S. Environmental Protection Agency (EPA). The mention of company or product names in this document is not to be considered an endorsement by the U.S. Government or by the EPA. This technical document consists of a brief review of acid forming processes at mine sites, followed by a summary of the current methods used to predict acid formation, selected state regulatory requirements, and case histories. This report was distributed for review to the U.S. Department of the Interior's Bureau of Mines and Bureau of Land Management, the U.S. Department of Agriculture's Forest Service, the Interstate Mining Compact Commission, the American Mining Congress, the Mineral Policy Center, representatives of state agencies, and public interest groups. EPA is grateful to all individuals who took the time to review this technical document. The use of the terms "extraction," "beneficiation," and "mineral processing" in this document is not intended to classify any waste stream for the purposes of regulatory interpretation or application. Rather, these terms are used in the context of common industry terminology. Acid Mine Drainage Prediction TABLE OF CONTENTS Page 1. INTRODUCTION ................................................................ 1 1.1 Oxidation of Metal Sulfides ..................................................... 4 1.2 Source of Acid and Contributing Factors ........................................... 5 2. ACID GENERATION PREDICTION ................................................. 9 2.1 Sampling .................................................................... 11 2.2 Static Tests ................................................................. -
Properties of Acids
Properties of Acids Solutions of acids have a sour taste Don’t taste them in the lab !!! 1 They change the colors of many indicators Acids turn blue litmus to red Acids turn bromothymol blue from blue to yellow They react with metals to generate hydrogen gas, H2 1 Metal Activity Series More active Li, K, Ca, Na, Mg, Al, Mn, Zn, Fe, Co, Ni, Pb, H, Cu, Hg, Ag, Pt, Au Less active Active enough to displace Cannot displace hydrogen from an acid hydrogen from an acid 2 Properties of Acids They react with metal oxides forming the salt of the metal and water CaO + 2HCl → CaCl2 + H2O They react with metal hydroxides forming the salt of the metal and water Ca(OH)2 + 2HCl → CaCl2 + 2H2O 3 Oxides Compounds of oxygen and another element There are two ways to name oxides Based on the oxidation number of the element Li2O – lithium oxide BaO – barium oxide FeO – iron(II) oxide Fe2O3 – iron(III) oxide Based on the number of atoms of each element Li2O – dilithium oxide BaO – barium oxide FeO – iron oxide Fe2O3 – diiron trioxide 4 Example 1 Name the following compounds: BeO, Al2O3, Cu2O, OsO4, Cr2O3, CrO3 5 Example 2 Write formulas for the following compounds: Potassium oxide Boron oxide Diindium trioxide Cobalt(II) oxide Dinitrogen pentoxide Rhenium(VI) oxide Xenon tetroxide Carbon monoxide Carbon dioxide Manganese(VII) oxide 6 Example 3 Write total and net ionic equations for the reaction between cobalt (III) oxide and diluted hydroiodic acid 7 Example 4 Write total and net ionic equations for the reaction between dialuminum -
Acids and Bases
Acids and Bases 362 2020 Lecture 15 Lewis approach to acid/base interactions Gilbert Newton Lewis 1875 – 1946 Lewis Concept Lewis, 1930s: Base is a donor of an electron pair. Acid is an acceptor of an electron pair. For a species to function as a Lewis acid, it needs to have an accessible empty orbital. For a species to function as a Lewis base it needs to have an accessible electron pair. + + 6+ Examples of Lewis acids: BF3, AlCl3, SbF5, Na , H , S , etc. - Examples of Lewis bases: F , H2O, Me3N, C2H4, Xe, etc. Lewis Continued A more general view also classifies compounds that can generate a species with an empty orbital as Lewis acids. Then we can include B2H6, Al2Cl6, HCl etc. Since H+ and any cation from a solvent autodissociation is a Lewis acid, and anything that can add H+ or a solvent- derived cation is a Lewis base, the Lewis acid concept effectively includes the ones discussed previously. Lewis Continued Acid-base reactions under the Lewis model are the reactions of forming adducts between Lewis acids and bases. BF3 + Me3N F3B-NMe3 HF + F- FHF- - 2- SiF4 + 2F SiF6 - - CO2 + OH HCO3 TiCl4 + 2Et2O TiCl4(OEt2)2 In fact, any chemical compound can be mentally disassembled into Lewis acids and bases: 6+ - S + 6F SF6 4+ - - + - C + 3H + NH2 CH3 + NH2 Lewis Acids & Bases Other good examples involve metal ions. ••• •O—H 2+ •• 2+ Co • O—H Co • H ACID BASE H 2+ [Co(H2O)6] Empty d2sp3 hybrids on Cobalt account for the Lewis Acid/Base interactions Lewis Acids & Bases The combination of metal ions (Lewis acids) with Lewis bases such as H2O and NH3 ------> COMPLEX IONS All metal ions form complex ions with water —and are of n+ the type [M(H2O)x] where x = 4 and 6.