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Strong acids vs Weak acids

Strong acids vs Weak acids . Strong Acids- do dissociate completely Weak Acids – do not dissociate completely The strong acids are: HNO 3 H 2 SO 4 HCl HIO 4 HClO 4 HBr HClO 3 HI. Strong acids vs Weak acids…equations. HCl  H + + Cl -

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Strong acids vs Weak acids

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  1. Strong acids vs Weak acids • Strong Acids- do dissociate completely • Weak Acids – do not dissociate completely The strong acids are: HNO3 H2SO4 HCl HIO4 HClO4HBr HClO3 HI

  2. Strong acids vs Weak acids…equations • HCl H+ + Cl- • Single arrow in the equation because all of the HCl particles dissociate, this contributes large amounts of H+ to the solution • HC2H3O2 H+ + C2H3O2- • Double arrow, very few of the HC2H3O2 particles fall apart, contributing a smaller amount of H+ to the solution

  3. Bronsted Lowry Acids and Bases Acids - donate hydrogen ions (protons) Bases - accept hydrogen ions (protons) NH3+ H2O NH4++ OH- When you look at the reaction from left to right, NH3 is a base because it is accepting a hydrogen, and H2O is an acid because it is donating a hydrogen.

  4. Conjugate Acid/Base Pairs NH3 + H2O  NH4+ + OH- • Reading the reaction from right to left, NH4+ 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.

  5. NH3 + H2O  NH4++ OH- Base Acid Conjugate Conjugate Acid Base Water can act as an acid or a base, it is amphoteric

  6. Ka Weak acids have a Ka = acid dissociation constant • This is used to compare the strength of weak acids • HC2H3O2Ka = 1.8 x 10-5 • HF Ka = 7.2 x 10-4 • HC2H3O2 is a weaker acids because Ka is smaller

  7. Kw Water falls apart to a small extent H2O  H+ + OH- • [H+] = 1.0 x 10-7 M • [OH-] = 1.0 x 10-7 M • Kw = [H+] [OH-] • Kw = 1.0 x 10-14 • To calculate [H+] use [H+] =1.0 x 10-7M/[OH-] • To calculate [OH-] use [OH-] =1.0 x 10-7 M/[H+]

  8. Calculating pH from [H+] 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

  9. Given pH find [H+] • 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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