Chapter 15 Acids and Bases

Some Properties of Acids þ Produce H + (_______) ions in water (the ________ ion is a hydrogen ion attached to a water molecule) þ Taste ______ þ ______metals þ _____________ þ React with bases to form a ____ and ____ þ pH is less than______ þ Turns ______ litmus paper to ___ “___________”

Some Properties of Bases  Produce _____ ions in water  Taste ______, ______  Are ________  Feel _______, _______  React with acids to form _____and _____  pH greater than ____  Turns ____ litmus paper to _____ “_________”

Acid Nomenclature Review No Oxygen  w/Oxygen An easy way to remember which goes with which… “In the cafeteria, you ATE something ICky”

___________ is a substance that produces ______in water __________ is a substance that produces _____in water 4.3 Acid/Base definitions Definition 1: _________

Acid/Base Definitions Definition #2: __________Definition #2: __________ Acids – ________ donor Bases – _______ acceptor A “proton” is really just a ______ atom that has lost it’s electron!

A Brønsted-Lowry ______ is a _____ donor A Brønsted-Lowry _______ is a _____acceptor bas

ACID-BASE THEORIES The Brønsted definition means _____ is a BASE in water — and _________an ACID

Conjugate Pairs

Learning Check! Label the acid, base, conjugate acid, and conjugate base in each reaction: HCl + OH -  Cl - + H 2 O H 2 O + H 2 SO 4  HSO H 3 O +

Acids & Base Definitions Lewis acid - a substance that ______an_____________ Lewis base - a substance that _______an___________. Definition #3 – ______

Formation of ___________is also an excellent example. Lewis Acids & Bases _____________of the new O-H bond originates on the Lewis_________._____________of the new O-H bond originates on the Lewis_________.

Lewis Acid/Base Reaction

The pH scale is a way of expressing the strength of acids and bases. Under 7 = _______ 7 = _______ Over 7 = _______

Calculating the pH Equation: ____________ (Remember that the [ ] mean________) Example: If [H + ] = 1 X pH = - log 1 X pH = - (- 10) pH = 10 Example: If [H + ] = 1.8 X pH = - log 1.8 X pH = - (- 4.74) pH = 4.74

Try These! Find the pH of these: 1)A 0.15 M solution of Hydrochloric acid 2) A 3.00 X M solution of Nitric acid

pH calculations – Solving for H+ If the pH of Coke is 3.12, [H + ] = ???

More About Water H 2 O can function as both an _____and a______. In pure water there can be________________ Equilibrium constant for water = K w K w = [H 3 O + ] [OH - ] = _________at 25 o C

More About Water K w = [H 3 O + ] [OH - ] = _________at 25 o C In a neutral solution [_____________ and so_______________________ Autoionization

pOH Since acids and bases are opposites, ______and _______are opposites!Since acids and bases are opposites, ______and _______are opposites! _______looks at the perspective of a base_______looks at the perspective of a base________ Since ____and _______are on opposite ends, Since ____and _______are on opposite ends,_____________

pH [H + ] [OH - ] pOH

[H 3 O + ], [OH - ] and pH What is the pH of the M NaOH solution?

What is the pH of a 2 x M HNO 3 solution? Start End What is the pH of a 1.8 x M Ba(OH) 2 solution? Start End

HNO 3, HCl, HBr, HI, H 2 SO 4 and HClO 4 are the __________acids. Strong and Weak Acids/Bases The strength of an acid (or base) is determined by the amount of_________________.

Generally divide acids and bases into STRONG or WEAK ones.Generally divide acids and bases into STRONG or WEAK ones. STRONG ACID: HNO 3 (aq) + H 2 O (l)  H 3 O + (aq) + NO 3 - (aq) HNO 3 is about 100% dissociated in water. Strong and Weak Acids/Bases

_________are much less than ________ionized in water._________are much less than ________ionized in water. Strong and Weak Acids/Bases

________: _______dissociated in water.________: _______dissociated in water. NaOH (aq)  Na + (aq) + OH - (aq) NaOH (aq)  Na + (aq) + OH - (aq) Other common strong bases include KOH and Ca(OH) 2. CaO (lime) + H 2 O --> Ca(OH) 2 (slaked lime) Ca(OH) 2 (slaked lime) CaO Strong and Weak Acids/Bases Strong bases are the __________ ____________________are strong, but only soluble in water to 0.01 M

Weak ________: less than _______ionized in waterWeak ________: less than _______ionized in water One of the best known_____________. NH 3 (aq) + H 2 O (l) ↔ NH 4 + (aq) + OH - (aq) Strong and Weak Acids/Bases

Weak Bases

Equilibria Involving Weak Acids and Bases

Ionization Constants for Acids/Bases Acids ConjugateBases Increase strength

Equilibrium Constants for Weak Acids

Equilibria Involving A Weak Acid You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH.

Equilibria Involving A Weak Acid

You have 1.00 M HOAc. Calc. the equilibrium concs. of HOAc, H 3 O +, OAc -, and the pH.

Equilibria Involving A Weak Acid

Calculate the pH of a M solution of formic acid, HCO 2 H. HCO 2 H + H 2 O ↔ HCO H 3 O + HCO 2 H + H 2 O ↔ HCO H 3 O + K a = 1.8 x 10 -4

Equilibrium Constants for Weak Bases

Relation of K a, K b, [H 3 O + ] and pH

Equilibria Involving A Weak Base You have M NH 3. Calc. the pH. NH 3 + H 2 O ↔ NH OH - NH 3 + H 2 O ↔ NH OH - K b = 1.8 x 10 -5

Equilibria Involving A Weak Base You have M NH 3. Calc. the pH. NH 3 + H 2 O  NH OH - NH 3 + H 2 O  NH OH - K b = 1.8 x 10 -5

Equilibria Involving A Weak Base You have M NH 3. Calc. the pH. NH 3 + H 2 O  NH OH - NH 3 + H 2 O  NH OH - K b = 1.8 x 10 -5

Types of Acid/Base Reactions: Summary

F - (aq) + H 2 O (l) OH - (aq) + HF (aq) Weak Bases are _________ electrolytes NO 2 - (aq) + H 2 O (l) OH - (aq) + HNO 2 (aq) Conjugate acid-base pairs: The conjugate base of a strong acid has no measurable strength. strongest acid _______ the strongest acid that can exist in aqueous solution. strongest baseThe ______is the strongest base that can exist in aqueous solution. 15.4

Strong AcidWeak Acid 15.4

percent ionization = x 100% For a monoprotic acid HA Percent ionization = [H + ] [HA] 0 x 100% [HA] 0 = initial concentration 15.5

15.7 Ionization Constants of Conjugate Acid-Base Pairs KaKa KbKb KwKw

Molecular Structure and Acid Strength H X H + + X

Molecular Structure and Acid Strength Z O HZ O-O- + H + -- ++ 15.9

Molecular Structure and Acid Strength ________ having different central atoms (Z) that are from the same group and that have the same oxidation number. Acid strength increases with increasing electronegativity of Z H O Cl O O H O Br O O Cl is more _____________than Br HClO 3 > HBrO

Molecular Structure and Acid Strength 2. ___________having the same central atom (Z) but different numbers of attached groups. Acid strength __________as the oxidation number of Z increases. HClO 4 > HClO 3 > HClO 2 > HClO 15.9

Acid-Base Properties of Salts Neutral Solutions: Salts containing an alkali metal or alkaline earth metal ion (except Be 2+ ) and the conjugate base of a strong acid (e.g. Cl -, Br -, and NO 3 - ). NaCl (s) Na + (aq) + Cl - (aq) H2OH2O Basic Solutions: Salts derived from a strong base and a weak acid. NaCH 3 COO (s) Na + (aq) + CH 3 COO - (aq) H2OH2O CH 3 COO - (aq) + H 2 O (l) CH 3 COOH (aq) + OH - (aq) 15.10

Acid-Base Properties of Salts Acid Solutions: Salts derived from a strong acid and a weak base. NH 4 Cl (s) NH 4 + (aq) + Cl - (aq) H2OH2O NH 4 + (aq) NH 3 (aq) + H + (aq) Salts with small, highly charged metal cations (e.g. Al 3+, Cr 3+, and Be 2+ ) and the conjugate base of a strong acid. Al(H 2 O) 6 (aq) Al(OH)(H 2 O) 5 (aq) + H + (aq)

Acid-Base Properties of Salts Solutions in which both the cation and the anion hydrolyze: K b for the anion > K a for the cation, solution will be basic K b for the anion < K a for the cation, solution will be acidic K b for the anion  K a for the cation, solution will be neutral 15.10