Acids and Bases Ch.14/15

The Battle to define them Arrhenius was first in 1884 Acids: something that produces H + ions in solution. Bases: something that produces OH - ions in solution. Have OH - in them or remove H + from water and leave an OH -

The Battle to define them Bronsted and Lowry were next Acids: something that donates H + (proton) Bases: something that accepts H + HCl (g) + H 2 O (l)  H 3 O + (aq) + Cl - (aq) acid base H 3 O + - Hydrodium ion

The Battle to define them Lewis Acids/Bases Acids: particle (atom, ion, molecule) that accepts an e - pair to form covalent bond Bases: particle that donates an e - pair H + + :NH 3  H-NH 3 (NH 4 + ) acid base

Properties of acids Taste Sour Lemonade, OJ, pop, vinegar Change the color of indicators Some react with metals to release H 2 React with bases  salt and water Electrolyte – conducts electricity when in water

Properties of bases Taste bitter Change the color of indicators Feel slippery React with acids  salt and water Electrolyte

Review Naming Acids oxyacids: hydrogen and polyatomic ion (with oxygen) Change ending of polyatomic ion ite  ous ate  ic binary: hydrogen and nonmetal(s) Hydro__________ic Acid

Naming Acids HF HClO 4 HI HNO 3 H 2 SO 3 HCN

Conjugate Acid and Base Conjugate acid (CA): the base + H + Conjugate base (CB): the acid without its H + HCl (g) + H 2 O (l)  H 3 O + (aq) + Cl - (aq) acid base CACB

Strengths of CA and CB Strong Acids  weak CB Strong Bases  weak CA Opposite is true… Weak Acid  stronger CB, etc.

Conjugate Acid and Base Identify acid, base, CA and CB: H 3 O + (aq) + NH 3(aq)  H 2 O (l) + NH 4 + (aq) HCl (aq) + NH 3(aq)  NH 4 + (aq) + Cl - (aq) HCO 3 - (aq) + HF (aq)  H 2 CO 3(aq) + F - (aq)

Neutralization Reactions Acid + Base  Salt + water Salt = an ionic compound Water = HOH Base = has to have OH - HNO 3(aq) + KOH (aq)  KNO 3(aq) + HOH (l)

Strength Strong acids and bases are strong electrolytes Mainly separated ions  they fall apart completely NaOH is a strong base- it falls completely apart when dissolved. Weak acids and bases are weak electrolytes  don’t completely ionize = not as many ions in solution

Strength p. 485 Strong Acids: HClH 2 SO 4 HIHNO 3 HClO 4 Weak Acids: H 3 PO 4 HC 2 H 3 O 2 H 2 CO 3 HFHCN

Strength p. 485 Strong Bases: Alkali metal hydroxides, NaOH, KOH, etc. CaO Weak Bases: NH 3

pH pH is a measure of strength – how many H + pH of 7 = neutral pH less than 7 = acidic The lower the pH the stronger the acid pH greater than 7 = basic The higher the pH the stronger the base

Calculating pH Measures concentration of H +  [H + ] pH = -log[H + ] A lot of H + = strong acid = lower pH Few H + = weak acid = higher pH

Calculating pH Powers of ten A shorthand for big, or small numbers. What is the pH of a solution with [H + ] = 4.8 x M?

Calculating pH Can find [H + ] if know the pH [H + ] = 10 - pH OJ has a pH of 3.5. What is the [H + ] of OJ?

Calculating pOH pOH = -log[OH - ] pH + pOH = 14 [OH - ] = 10 -pOH If the pH of a solution is 5.5, what is the [OH - ]?