Acids and Bases CN

Properties of Acids and Bases

Acids:

  • aq. solutions → sour taste

  • change color of acid-base indicators (litmus paper)

    • blue paper → red in acid

    • red paper → blue base

  • some react with active metals and release H2 gas

    • Ba (s) + H2SO4(aq) → BaSO3(s) + H2(g)

  • acid + base → salt (ionic compound) + H2O

  • conduct electric currents (electrolytes)

    • strong: lots of ions; weak: not many ions

Acid Nomenclature

  • binary acid: contains only 2 diff. elements

    • hydrogen and one of more electronegative elements

    • HF, HCl, HBr, HI

  • begins with hydro-

  • root of name of 2nd elements follows this prefix

  • ends with -ic

    • H2S

  • ocyacid: compound of hydrogen, oxygen, and third element (usually nonmetal)

    • names of anions based on names of acids

Bases

  • aq solution taste bitter

  • change color of acid-base indicators

  • diluted feels slippery

  • acid + base → salt (ionic compound) + H2O

  • conduct current

Acid-Base Theories

Arrhenius Acids and Bases

  • arrhenius acid: chem compound that inc. concentration of Hydrogen Ions, H+, in aq sol.

    • ionizable hydrogen atoms (water sol. known as aqueous acids)

    • when 2 or more hydrogen per oxygen is strong

    • weak acids hold their H ions

    • strong acid ionizes completely (almost) in aq sol. → good electrolytes (separate ions, lots) (Cl, Br, I with H dissociates the most)

    • weak acid releases few hydrogen ions in sq sol.

    • hydronium ions, anions, dissolved acid, HCN, (anything with —COOH)

  • arrhenius base: substance that inc. concentration of Hydroxide Ions, OH-, in aq sol.

    • most are ionic compounds w/ metal cations and hydroxide anion, OH-

    • dissociate in H2O (example) NaOH (s) + H2O → Na (aq) + OH- (aq)

    • Ammonia NH3 is molecular → produces hydroxide ions when reacts w/ H2O molecules (example) NH3 (aq) + H2O (I) → NH4 (aq) + OH- (aq)

    • strong bases: (all group 1, heavy group 2 from Calcium) very soluble (strong electrolytes)

    • weak bases: doesn’t grab every water molecule, only few do

Bronsted and Lowry acid and base

  • acid: proton donor

  • HCl + NH3 → NH4 + Cl (HCl as Bronsted Lowry acid)

  • base: proton acceptor

  • HCl + NH3 → NH4 + Cl (NH3 as Bronsted Lowry base)

    • OH- ion produced in solution by arrhenius hydroxide bases (NaOH) is the Bronsted-Lowry base

  • acid transfer protons to bases

    • what becomes of base after it does is job → becomes conjugate acid

    • what becomes of acid after it does its job → becomes conjugate base

Monoprotic and Polyprotic Acids and Bases

  • Monoprotic Acid: can donate only one proton (hydrogen ion) per molecule

    • HClO, HCl, HNO3

    • only one ionization step

mono ---di

Polyprotic Acid: donates more than one proton per molecule

  • multiple ionization steps

Diprotic Acid: donate two protons per molecule

  • H2SO4

Triprotic Acid: donate three protons per molecule

  • H3PO4

Acid-Base Reactions

Conjugate Acid and Bases

  • conjugate base: Bronsted lowry acid that has given up a proton

  • conjugate acid: bronsted lowry base that has gained a proton

  • Stronger an acid is → weaker conjugate base

  • stronger a base is → weaker conjugate acid

  • Proton transfer goes in direction of stonger base

    • which base is better at grabbing protons?

  • strong acid favors right

  • weak acid favors left

Amphoteric Compounds

  • any species can act as either an acid or base

    • ex. Water can be either base or acid

Neutralization Reactions

  • neutralization: H+ reacts w/ OH- to form water molecules

  • salt: ionic compound made of cation from base and anion from acid

H+ + -OH → H2O

Acid rain

  • NO, NO2, CO2, SO2, SO3 (g) from industrial processes can dissolve in atmospheric H2O → acidic solutions

    • very acidic rain is known as acid rain

    • erode many things & can affect ecosystems