U2 S1 L2 Bronsted Lowry p 553 Homework: p 557 # 1 – 9 p 558 section review # 1 -11 (answers on page 581)

Upon completion of this lesson, you will be able to: define Brønsted-Lowry acids and bases define conjugate species identify the Brønsted-Lowry acid, base, conjugate acid and conjugate base in a Brønsted-Lowry acid-base equation define and identify amphoteric substances as examples of species that can either accept or donate a proton illustrate the amphoteric nature of water by writing chemical equations where water acts as an acid when combined with a stronger base and where water acts as a base when combined with a stronger acid compare Arrhenius acid-base theory with Brønsted-Lowry acid-base theory

Bronsted-Lowry Theory: Commonly called the proton transfer theory. An acid is a chemical species (cation, anion, or molecule) that loses protons (H+) in a chemical reaction. A base is a chemical species (cation, anion, or molecule) that gains protons (H+) in a chemical reaction. An acid/base reaction is a reaction in which a proton is transferred from an acid to a base.

Amphoterism An amphoteric species can act as an acid in one reaction and as a base in another reaction. That is, they can either gain or lose a proton (H+) depending on what it is reacting with.

An amphoteric (sometimes called amphiprotic) species must have at least one removable hydrogen atom and have "room" to accept one additional proton in an acid-base reaction. Show that water is an amphoteric species by writing an acid-base equation for water reacting with: boric acid, H3BO3   ethanamine, CH3CH2NH2   Show how HSO3- is amphoteric.

Classify each species as amphoteric or not amphoteric Classify each species as amphoteric or not amphoteric. Justify your choices. hydrosulfuric acid, H2S (aq)   fluoride ion, F-(aq)  hydrogen oxalate, HOOCCOO-(aq)  hydrogen phosphate, HPO42-(aq)   cyanide ion, CN-(aq)