ACIDS AND BASES

Properties  electrolytes  turn litmus red  sour taste  react with metals to form H 2 gas  slippery feel  turn litmus blue  bitter taste ChemASAP  vinegar, milk, soda, apples, citrus fruits  ammonia, lye, antacid, baking soda

Acids are Proton (H + ion) Donors Strong acids are assumed to be 100% ionized in solution (good H + donors). Weak acids are usually less than 5% ionized in solution (poor H + donors). HCl H 2 SO 4 HNO 3 H 3 PO 4 HC2H3O2HC2H3O2 Organic acids

Acids Have a pH less than 7

Acids Taste Sour  Citric acid in citrus fruit  Malic acid in sour apples  Lactic acid in sour milk and sore muscles  Butyric acid in rancid butter Organic acids are weak acids. Some are used as flavoring agents in food.

Acids Effect Indicators Blue litmus paper turns red in contact with an acid. Methyl orange turns red with addition of an acid

Acids React with Active Metals Acids react with active metals to form salts and hydrogen gas. Mg + 2HCl  MgCl 2 + H 2 (g) Zn + 2HCl  ZnCl 2 + H 2 (g) Mg + H 2 SO 4  MgSO 4 + H 2 (g)

Acids React with Carbonates 2HC 2 H 3 O 2 + Na 2 CO 3 2 NaC 2 H 3 O 2 + H 2 O + CO 2

Effects of Acid Rain on Marble (calcium carbonate) George Washington: BEFORE George Washington: AFTER

Acids Neutralize Bases HCl + NaOH  NaCl + H 2 O Neutralization reactions ALWAYS produce a salt and water. H 2 SO 4 + 2NaOH  Na 2 SO 4 + 2H 2 O 2HNO 3 + Mg(OH) 2  Mg(NO 3 ) 2 + 2H 2 O OH - (hydroxide) in base combines with H + in acids to form water H + + OH -  H 2 O

Definitions  Brønsted-Lowry HCl + H 2 O  Cl – + H 3 O + AcidsAcids are proton (H + ) donors. BasesBases are proton (H + ) acceptors. conjugate acid conjugate base baseacid

Definitions H 2 O + HNO 3  H 3 O + + NO 3 – CBCAAB

Definitions - can be an acid or a base.  Amphoteric - can be an acid or a base. NH 3 + H 2 O  NH OH - CACBBA

Definitions F - H 2 PO 4 - H2OH2O HF H 3 PO 4 H 3 O +  Give the conjugate base for each of the following: (these are acids)

Definitions Br - HSO 4 - CO 3 2- HBr H 2 SO 4 HCO 3 -  Give the conjugate acid for each of the following: (these are bases-accept protons)

Acid/Base Definitions TypeAcidBase Bronsted- Lowry H+ donorH+ acceptor

Properties of Bases  Bases are proton (hydrogen ion, H + ) acceptors  Bases have a pH greater than 7  Bases taste bitter  Effects on indicators-  Red litmus turns blue  Phenolphthalein turns purple  Solutions of bases feel slippery  Bases neutralize acids

Bases are Proton (H + ion) Acceptors  Sodium hydroxide (lye), NaOH  Potassium hydroxide, KOH  Magnesium hydroxide, Mg(OH) 2  Calcium hydroxide (lime), Ca(OH) 2

Bases have a pH greater than 7

Bases Effect Indicators Red litmus paper turns blue in contact with a base. Phenolphthalein turns bright pink in a base.

Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH) 2, which neutralizes stomach acid, HCl. 2 HCl + Mg(OH) 2 MgCl H 2 O