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Published byGregory Sharp Modified over 8 years ago
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Strong Acids- do dissociate completely Weak Acids – do not dissociate completely The strong acids are: HNO 3 H 2 SO 4 HClHIO 4 HClO 4 HBr HClO 3 HI
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HCl H + + Cl - ◦ Single arrow in the equation because all of the HCl particles dissociate, this contributes large amounts of H + to the solution HC 2 H 3 O 2 H + + C 2 H 3 O 2 - ◦ Double arrow, very few of the HC 2 H 3 O 2 particles fall apart, contributing a smaller amount of H + to the solution
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Acids - donate hydrogen ions (protons) Bases - accept hydrogen ions (protons) NH 3 + H 2 O NH 4 + + OH - W hen you look at the reaction from left to right, NH 3 is a base because it is accepting a hydrogen, and H 2 O is an acid because it is donating a hydrogen.
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NH 3 + H 2 O NH 4 + + OH - Reading the reaction from right to left, NH 4 + is an acid because it is donating a hydrogen and OH - is a base because it is accepting a hydrogen. These are conjugate acid - base pairs.
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NH 3 + H 2 O NH 4 + + OH - Base Acid Conjugate Conjugate Acid Base Water can act as an acid or a base, it is amphoteric
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Weak acids have a Ka = acid dissociation constant This is used to compare the strength of weak acids HC 2 H 3 O 2 Ka = 1.8 x 10 -5 HF Ka = 7.2 x 10 -4 HC 2 H 3 O 2 is a weaker acids because Ka is smaller
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Water falls apart to a small extent H 2 O H + + OH - [H + ] = 1.0 x 10 -7 M [OH - ] = 1.0 x 10 -7 M K w = [H + ] [OH - ] K w = 1.0 x 10 -14 To calculate [H + ] use [H + ] =1.0 x 10 -7 M/[OH - ] To calculate [ OH - ] use [ OH - ] =1.0 x 10 -7 M/[H + ]
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pH = -log[H + ] pH + pOH = 14 pOH =-log[OH - ] Example : [H + ] = 1.0 x 10 -4 M pH = - log (1.0 x 10 -4 ) pH = 4 pOH = 14 - 4 =10
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The opposite of log is antilog, this function is located above log on your calculator. [H + ] = 10 ^ -pH [OH - ] = 10 ^ -pOH pH = 6 10 ^-6 = 1.0 x 10 -6
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