16 - Acids and Bases

16 - Acids and Bases - Chapter 16: Acids and Bases...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 16: Acids and Bases hydronium ions, H 3 O + , are responsible for properties of acidic aqueous solutions, and hydroxide ions, OH - , are responsible for the properties of basic aqueous solutions because of their small size and high charge density, hydrogen ions (protons) are always associated with water molecules in aqueous solution are represented as H 3 O + 16.1The Bronsted-Lowry Concept of Acids and Bases Bronsted-Lowry acids are hydrogen ion donors Bronsted-Lowry bases are hydrogen ion acceptors, must have an unshared pair of electrons in acid-base reactions , acids donate H + ions, and bases accept them ionization of strong acids is a product-favored reaction that is almost 100% ionized ionization of weak acids is a reactant-favored reaction and most molecules at equilibrium are unionized Water’s Role as Acid or Base o water acting as a base: HA+H 2 O H 3 O + +A - ; HA=acid; A - =conjugate base o water acting as an acid: B+H 2 O BH + +OH - ; B=base; BH + =conjugate acid o amphiprotic describes a substance that can donate or accept H + Conjugate Acid-Base Pairs o conjugate acid-base pair is a pair of molecules or ions related to each other by the loss or gain of a single H + ; every Bronsted-Lowry acid has a conjugate base and every base has a conjugate acid o one member of the conjugate acid-base pair is always a reactant and the other a product; never both reactants or both products Relative Strengths of Acids and Bases o strong acids are better H + donors but have weaker conjugate bases o strong bases are better H + acceptors but have weaker conjugate acids o as acid strength decreases, conjugate base strength increases; the weaker the acid, the stronger the conjugate base o as base strength decreases, conjugate acid strength increases; the weaker the base, the stronger the conjugate acid o the stronger acid and the stronger base will always react to form a weaker conjugate base and a weaker conjugate acid o acid-base reactions favor going from stronger to weaker member of each conjugate acid-base pair 16.2Carboxylic Acids and Amines in carboxylic acids, only the hydrogen bonded to the oxygen is able to be donated because the highly electronegative oxygen atoms pull electron density away from hydrogen atom; the other hydrogen atoms are nonacidic anions formed by loss of hydrogen from a carboxylic group are stabilized by resonance amines are compounds like ammonia that have a nitrogen atom with three of its valence electrons in covalent bonds and an unshared electron pair on the nitrogen atom; lone pair can accept an H + so it reacts with water 16.3The Autoionization of Water autoionization is process in which water molecules react to produce hydronium ions and hydroxide ions ionization constant for water is K w =[H 3 O + ][OH - ] and applies to pure water and all aqueous solutions; temperature dependent; K w =1.0x10 -14 at 25 degrees Celsius
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/28/2009 for the course CHEM 1A taught by Professor Nitsche during the Fall '08 term at Berkeley.

Page1 / 4

16 - Acids and Bases - Chapter 16: Acids and Bases...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online