# PH (potential of Hydrogen). According to the Bronsted-Lowry theory, both acids and bases are related to the concentration of hydrogen ions. Acids will.

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pH (potential of Hydrogen)

According to the Bronsted-Lowry theory, both acids and bases are related to the concentration of hydrogen ions. Acids will increase the amount of hydrogen ions in a solution. Bases will decrease the amount of hydrogen in a solution.

Gives value to strength of an acid. pH = -log [H + ] [H+] = Concentration of Hydrogen pH increases as [H+] decreases Neutral pH is 7 (water) pH Scale

pH = -log [H + ] [H + ] = 10 -pH pOH = -log [OH - ] [OH - ] = 10 -pOH

pOH = 14 – pH pH = 14 – pOH

Strong Acids & Bases – Dissociate completely in solution – Strong Electrolytes – Strong Acids: HCl, HBr, HI, HClO 4, H 2 SO 4, HNO 3 pH < 4.0 – Strong Bases: Group 1 or 2 metal hydroxides Examples: KOH, Ba(OH) 2 pH > 10.0

Weak Acids & Bases – Dissociate partially in solution – Weak electrolytes – Weak Acids: Any acid not listed as a strong acid on previous slide pH: 4.0-6.9 – Weak Bases: Anything other than a group 1 or 2 metal hydroxide pH: 7.1-9.9

Example A solution has a pH of 4.7. Calculate the pOH, [H+] and [OH-]. Is it acidic, basic, or neutral? – pOH = 14.00- 4.7 = 9.3 – acidic

Example 3 Find the pH of a 1.0x10 -3 M NaOH solution NaOH  Na + + OH -

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