Acids and Bases

Recall

• Acids are compounds that start with hydrogen (H+)– HCl (hydrochloric acid)

– H2SO4 (sulfuric acid)

• Bases are compounds that end with hydroxide (OH-)– NaOH (sodium hydroxide)

– Mg(OH)2 (magnesium hydroxide)

Properties of Acids• Sour tasting

• Turn blue litmus paper red• Electrolytes

• HBr(aq) H+(aq) + Br-

(aq)

• Neutralize bases • HCl(aq) + KOH(aq) KCl(aq) + H2O(l)

• React with metals to produce H2 (g)

• 2HNO3(aq) + Zn(s) H2(g) + Zn(NO3)2(aq)

• React with carbonates to produce CO2

• 2HCl + Na2CO3(s) → 2NaCl(aq) + CO2(aq) + H2O(l)

Common Acids

citric acid carbonic acid

acetic acid sulfuric acid

Properties of Bases• Bitter tasting• Slippery feel

• Turn red litmus paper blue

• Electrolytes • LiOH(aq) Li+(aq) + OH-

(aq)

• Neutralize acids • HCl(aq) + Mg(OH)2(s) MgCl2(aq) + H2O(l)

Common Bases

sodium hydroxidemagnesium hydroxide

sodium bicarbonate ammonia

Arrhenius’ Theory• An acid is a substance that dissociates in water to produce

one or more hydrogen ions (H+)

• A base is a substance that dissociates in water to form one or more hydroxide ions (OH-)

Percent Ionization• Percentage of molecules that form ions in solution

Strong Acids• Ionize completely (>99%) in water• [H+] = [Acid]• High electrical conductivity• Very low pH• The corrosive property of acids is attributed to the

hydrogen ion

Strong Bases

• Ionic hydroxides (NaOH, KOH, Ba(OH)2)

• Ionize completely (>99%) in water

• [OH-] = [Base]

• High electrical conductivity

• Very high pH

Weak Acids

• Percent ionization <50%

• [H+] < [Acid]

• Low electrical conductivity

• pH < 7

• Dilute weak acids are safer to handle and even to eat or drink

• Acetic acid, citric acid, carbonic acid

Weak Bases

• Percent ionization <50%

• Low electrical conductivity

• pH > 7

• Ammonia (NH3), sodium bicarbonate NaHCO3

Practice!

• P. 379 # 2-5,11

• P. 392 #1-4