Acids and Bases

Properties of Acids Have a sour taste Changes colors of substances called indicators Aqueous Solutions are electrolytes ( conduct electricity) React with metals: Zn + 2 HCl  ZnCl2 + H2 Reacts with carbonates: 2HCl + Na2CO3  2NaCl + H2O + CO2 Have at least one hydrogen atom attached to a negative ion. Reacts with (-OH) to form water pH below 7

Naming Acids Hydrogen comes first you know it’s an acid The second part determines the name Ends in “ide”… Acid name begins with hydro, the stem of the anion has the suffix “ic” and then acid is on the end Ends in “ite”… The stem of the anion has the suffix “ous” and then acid is on the end Ends in “ate”… The stem of the anion has the suffix “ic” and then acid is on the end Practice problems 1-5 pg 579

Properties of Bases Have a bitter taste Changes colors of indicators Feels slippery React with (H+) to form water pH above 7 No special naming structure just normal rules

Hydrogen Ions and Acidity Hydrogen Ions from Water Water self-ionizes H2O + H2O  H3O+ + OH- or H2O  H+ + OH- When water self-ionizes [H+] = [OH-] = 1.0 x 10-7 Kw = [H+][OH-] = (1.0 x 10-7)(1.0 x 10-7) = 1.0 x 10-14 Acid solutions-substance is added to water to increase [H+] so [H+] >1.0 x 10-7 Basic solutions-substance is added to water to increase [OH-] so [OH-] >1.0 x 10-7 Practice problems #6-7 pg 582

The pH Concept pH is a measurement of the acidity of solutions. pH=-log [H+] If pH>7 the solution is basic. If pH<7 the solution is acidic. If pH=7 the solution is neutral. pOH is a measurement of the basicity of solutions. pOH=-log [OH-] pH + pOH = 14. Also [H+][OH-] = 1.0 x 10-14 Practice problems #8-9 pg 586