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Podcast 12.5 pH and pOH. Acids. Taste sour Give a sharp stinging pain in a cut Reacts with metals Called a proton donor Have a high concentration of H+ ions Range from 0-6.9 on pH scale 0 = strongest acid 6.9 = weakest acid. Bases. Taste bitter Feels slippery (soap )
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Acids • Taste sour • Give a sharp stinging pain in a cut • Reacts with metals • Called a proton donor • Have a high concentration of H+ ions • Range from 0-6.9 on pH scale • 0 = strongest acid • 6.9 = weakest acid
Bases • Taste bitter • Feels slippery (soap) • Can dissolve organic matter • Called a proton acceptor • Have a high concentration of OH- ions • Range from 7.1-14 on pH scale • 14 = strongest base • 7.1 = weakest base
Acid – Base Reactions If you mix an acid with a base, it will either form water or neutralize. Reaction: H+ + OH- H2O
Acid Base Calculations • In neutral solutions, [H+] and [OH-] are ______________ • In water, [H+] = [OH-] = 1 x 10-7 M • For other solutions, when [H+] increases, then [OH-] will decrease and vise versa
Using the pH Scale • pH: Power of Hydrogen • pH = 7 Neutral [H+] = 1 x 10-7 • pH < 7 Acidic [H] > 1 x 10-7 • pH > 7 Basic [H+] = 1 x 10-7 • pH = _______[H+] • pOH : Power of Hydroxide • pOH = -log [OH-] • pH + pOH = 14
Using pH Scale Example 1: Calculate pH if [H+] = 1 x 10-7 M
Example 3 – Incomplete Dissociation What is the pHof a weak acid that is 8% dissociated as 0.100 M solution?