Acids and Bases

Arrhenius Acid & Base

Which beaker contains a base?

Bronsted Lowry Acid and Base Acid is a proton donor HF + H 2 O  H 3 O + + F- Base is a proton acceptor NH 3 + H  NH 4 + +H 2 0

Conjugate acid base pairs

Fill in the following table with the appropriate conjugate acid or base AcidBase H 2 SO 4 PO 4 3- NH 4 + F-F- H20H20 H20H20

Polyprotic acid MonoproticHCl, Cl- DiproticH 2 S, HS -, S 2- Diprotic H 2 SO 4, HSO 4 -, SO 4 2- TriproticH 3 PO 4, H 2 PO 4 -, HPO 4 2-, PO 4 3-

Naming acids Binary acids Hydro ____________ ic acid Ternary acids ______________ ic acid ______________ous acid

Name the following acids H 2 S (aq) H 2 SO 3 HClO 2 HNO 3 HF (aq) HC 2 H 3 O 2

Strong acids completely ionize in water

Strong acids (memorize)

Weak acids in water are in equilibrium They don’t completely Ionize in water Strong acids: Completely ionize in water

Bases donate OH - or accept H + NaOH Mg(OH) 2 Al(OH) 3 NH 3 PO 4 3-

Neutralization reactions Acid + base react to form salt + water HCl + NaOH  NaCl + H2O H 2 SO 4 + 2NaOH  Na 2 SO H 2 O How many moles of phosphoric acid are needed to react with 5.0 moles of sodium hydroxide?

Identify each of the following as an acid, base or salt AcidBaseSalt HC 2 H 3 O 2 MgCl 2 H 2 SO 4 Ca 3 (PO 4 ) 2 Sr(OH) 2 Al(NO 3 ) 3

Complete the following neutralization reactions and balance HBr + NaOH   CaCl 2 + H 2 O  Sr 3 (PO 4 ) 2 + H 2 O

pH=-log H 3 O +

Equations to determine pH Kw = [H ][OH - ] Kw = 1x pH = -log [H 3 O + ] [H ] = 10 –pH

Fill in the following graph pH[H 3 O+][OH-]Acid/base? x x x

pH[H 3 O+][OH-]Acid/base? x x10 -8 acid x x base x x acid x x acid x x base x base

compoundH3O+H3O+ OH - pH M HNO x10 -2 M KOH _____M HCl 2.3

Stomach produces HCl, how does it protect itself?

The acid in the stomach is hydrochloric acid, HCl, and has a pH of about 2. Acid of pH 2 can be quite corrosive - observe the effect of placing an iron nail in hydrochloric acid solution with pH =2

Buffer Buffer resists change in pH when small amounts of acid or base are added A buffer is a solution containing either a weak acid and its salt or a weak base and its salt,solutionweak acidsaltweak basesalt Weak acid + its salt is the acid and its conjugate base

Buffer system Weak acid Salt of the acid (conjugate base)

A Buffer consists of HSO 4 - and SO 4 2- NaOH is added to the solution. Who is the shark?

Did you pick HSO 4 - ? Write the reaction

A Buffer consists of H 2 CO 3 and HCO 3 - HCl is added to the solution. Who is the shark?

Predict whether each pair would form a buffer. Explain your answer. Pairs of compounds Explanation KOH, KCl HI, NaI NH 4 I, NH 3 NaH 2 PO 4, H 3 PO 4

Write an equation showing the buffering action of each of the following aqueous solutions NH 4 I / NH 3 adding OH- NaH 2 PO 4 /H 3 PO 4 adding H 3 O +

Buffers in the body

The body has many systems to control pH of the blood