Chemistry S2 - Acids and Bases

Properties of Acids

• taste sour

• pH < 7

• can be strong/weak electrolyte in H2O

Properties of Bases

• bitter, feel slippery

• pH > 7

• can be strong/weak electrolyte in H2O

Arrhenius Acids

• make H+ ions in aq. solution

• can be mono, di or triprotic

Arrhenius Bases

make OH- (hydroxide ion) ions in aq. solution

Bronsted-Lowry Acid

H+ (proton/hydronium ion) donors

Bronsted-Lowry Base

H+ acceptors

Conjugate Acid-Base Pairs

• reversible & at equilibrium

• products & reactants related by transfer of an H+ ion (proton)

Lewis Acid

electron-pair acceptor

Lewis Base

electron-pair donor

Hydrogen Ions in Water

water naturally self-ionizes into H+ & OH- ions

Neutral Solution

when [H+] = [OH-]

What is the concentration of H+ in water?

1.0 × 10^-7

Acidic Solution

has more H+ ions

Basic Solution

has more OH- ions

Measuring pH

• pH meters measure [H+] concentration

• can also use indicators

Indicators

chemicals that change colors at different pHs ex. blue & red litmus paper: bases turns red to blue, acids turn blue to red

Universal Indicator

mix of many indicators, has different color at each pH

Acid-Base Neutralization Reactions

reactions between acids & bases are double replacement reactions, generally produce water & an ionic compound (a neutral solution)

Titration

used to determine molarity of unknown acid/base by titrating it w/given amount of know acid/base

equation: M_aV_a = M_bV_b

Concentrated vs. Dilute (measure in molarity M)

< 1 M is dilute, > 1 M is concentrated

Strong vs. Weak

• strong acids & bases ionize/dissociate completely in solution NOT reversible

• weak acids & bases ionize only partially in solution, reversible reactions at equilibrium

What does it mean if the Ka/Kb is large?

the stronger the acid/base

Do we have to use ICE tables?

NO, just use initial concentration of acid/base