Acids and bases CH 15 and some of 16

strong bases (OH)

LiOH, NaOH, KOH

Strong base (OH)₂

Sr(OH)₂, Ca(OH)₂, Ba(OH)₂

Strong acids (H+something simple)

HCl, HBr, HI

Strong acids (complicated ones)

H₂SO₄, HNO₃, HClO₄

Strong acid+strong base=________ solution

Neutral

Weak acid+strong base=______ solution

Basic

Strong acid+weak base=_______ solution

Acidic

Weak acid+weak base=________

dependent on the relative acid-base strength of the two ions.

degree of ionization

[H₃O⁺]/Original given concentration

What are the concentrations of the hydrogen ion and acetate ion in a solution of 0.10 M acetic acid? What is the pH of the solution? What is the degree of ionization? STEPS

1. ICE Table

2. set up K_a (look up K_a value if not given)

3. Ca/Ka>100? If so, cancel out x in denominator

4. Solve for x to get concentrations of hydrogen ion (in this example hydronium) and acetate ion

5. find pH by -log[H₃O⁺]

6. find degree of ionization by [H₃O⁺]/0.10 M

if given two Ka values

1. make initial equilibrium equation

2. make second equilibrium equation using ion from the initial equilibrium equation

3. Use initial equilibrium equation to make ICE table

4. Use Ka1 to find x, which = [ion from initial equilibrium equation]

5. If asked for pH, use x value from step 4

6. make ICE table with the second equilibrium equation and the x value as the initial concentrations of the ion and [H₃O⁺]

7. find [ion] by solving for x

pH of a salt solution

1.0×10^-14

Determine Kb for an ion

1. Identify conjugate acid/base and identify their Ka or Kb value

2. Kb=Kw/Ka and Ka=Kw/Kb

3. substitute values

Common Ion Effect

Shift in ionic equilibrium caused by the addition of a solute that provides an ion to take part in the equilibrium

Common Ion effect example:

CH_3COOH+H_2O\lrArr CH_3COO^{-}+H_3O^{+}

If HCl is added, what way will equilibrium shift?

LEFT because adding HCl will ionize it into H+ and Cl- and H+=H3O+ so it’s adding products which means it would shift to the left.

Buffer systems ALWAYS consist of

a weak acid and its conjugate base OR a weak base and its conjugate acid

How to solve buffer equation (Steps, without Ka value)

1) Make equilibrium equation; put base/acid on left with water and conjugate acid/base on the right with H3O/OH

2) ICE Table with given molarities

3) Set up Ka or Kb equation (look up value if not given)

4)get rid of negligible x values

5) Solve for x, find pOH, pH, or whatever else you gotta do

*If Ka value is given, use Henderson-Hasselbalch equation

acid/base added to buffer system; how to find pH after addition

1) make equilibrium equation with given acid/bases

2) Find Ka (either in a table or find with Kb)

3) Henderson Hasselbalch ts out of the values to find pH BEFORE addition of strong acid/base

4) make equation showing addition of strong acid/base

5) Different ICE Table; Find initial M, change in M, and M after reaction

5a) Initial is given value, change is + or - the new strong acid/base (bc it is the limiting reagent), after reaction combines columns (strong acid/base will be 0)

6) Henderson Hasselbalch with new after reaction M values

7) if it asks for pH change, pH(final)-pH(initial)