# Lecture 112/14/05 Exam 1 Wednesday:  Come early if you want extra time Review session today 4 – TSC 006.

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Lecture 112/14/05 Exam 1 Wednesday:  Come early if you want extra time Review session today 4 – TSC 006

pH: Describes the concentration of H 3 O + pX = -log X pH = -log [H 3 O + ] [H 3 O + ] = 10 -pH So if [H 3 O + ] = 10 -3 M, pH = ? If pH = 6, [H 3 O + ] = ?

Autoionization of Water H 2 O + H 2 O ↔ H 3 O + + OH - K w = [H 3 O + ][OH - ] What is the definition of neutral, acidic, and basic solutions? Neutral: [H 3 O + ] = [OH - ] Acid: [H 3 O + ] >[OH - ] Base: [H 3 O + ] < [OH - ]

K w = [H 3 O + ][OH - ] THUS at 25°C, neutral pH = 7

T (°C)KwKw 100.29 x 10 -14 150.45 x 10 -14 200.68 x 10 -14 251.01 x 10 -14 301.47 x 10 -14 505.48 x 10 -14 Neutral pH = 7.27 Neutral pH = 6.92

pH and pOH K w = [H 3 O + ][OH - ] At 25 °C 10 -14 =[H 3 O + ][OH - ] -log (10 -14 =[H 3 O + ][OH - ]) -log (10 -14 ) = -log([H 3 O + ][OH - ]) -log (10 -14 ) = -log[H 3 O + ]-log[OH - ] 14 = pH + pOH

How do you measure pH? What is the pH range? pH meter Indicator (color change)

pH of some common substances pH Bleach12.5 Baking soda8.4 Egg White7.7 Milk6.8 Unpolluted rain5.6 Coffee4.9 Coke2.9 Stomach acid1.2

Degree of ionization

pH of strong acid? What is the pH of a 0.001 M HNO 3 solution?

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