Aqueous Reactions

Pb(NO3)2 (s) + H2O (l) lead nitrate(II)

KI (s)potassium iodide

+ H2O (l)

Pb2+ (aq) + 2 NO3- (aq) + K+ (aq) + I- (aq)

yellow solid + solution

PbI2 KNO3

Pb2+ (aq) + NO3- (aq)2

K+ (aq) + I- (aq)

displacement reactionsolubility of salts

Solubility rules1. Most NO3

- salts are soluble

2. Most salts of alkali metals (IA) and NH4+ are soluble

3. Most Cl-, Br- and I- salts are solubleExceptions: Ag+, Pb2+ and Hg2

2+ insoluble4. Most SO4

2- are soluble

Exceptions: Ca2+, Ba2+, Pb2+, Hg22+ insoluble

5. Most OH- are insolubleExceptions: IA, Ca2+, Ba2+, Sr2+ soluble

6. Most S2-, CO32-, CrO4

2-, PO43- insoluble

Exceptions: IA, NH4+ soluble

Pb2+ (aq) + 2 NO3- (aq) + K+ (aq) + I- (aq)

yellow solid + solution

PbI2 KNO3

2. Most IA salts are soluble

PbI2 (s) + K+ (aq) + NO3- (aq)

balance the equation

start with molecular equation

3. Most Cl-, Br- and I- salts are solubleExceptions: Ag+, Pb2+ and Hg2

2+ insoluble

1. Most NO3- salts are soluble

Pb(NO3)2 (aq) + KI (aq)

balance molecular equation

PbI2 (s) + KNO3 (aq)22

change to ionic equation

1. Most NO32- salts are soluble

Pb2+(aq)+2NO3-(aq)

2. Most Group I salts are soluble

3. Most Cl-, Br- and I- salts are soluble

except Ag+, Pb2+ and Hg22+

+2K+(aq) +2I-(aq) PbI2 (s) +2K+(aq) +2NO3- (aq)

spectator ions they can be cancelled out innet ionic equation

Pb2+(aq) + 2 I- (aq) PbI2 (s)

Acid/Base reactionsHCl strongdissociates completely

NaOH dissociates completely strong

H+(aq) Cl- (aq)

Na+(aq) OH-(aq)

H+(aq)

H2O (l)

+Cl-(aq)+ Na+(aq)+ OH-(aq)

acid

base

+ Na+(aq) + Cl-(aq)

HCl(aq)

molecular eqn

+ NaOH(aq) H2O(l) + NaCl(aq)

ionic eqn H+ +Cl-+ Na++ OH- H2O + Na++ Cl-

net ionic eqn H+ + OH- H2O

Acid/Base reactionsHCl strongdissociates completely

H+(aq) Cl- (aq)

acid

Mg(OH)2 does not dissociate completely

Mg(OH)2(aq)

weak base

H++ Cl-

Mg2+(aq) + 2OH-(aq)

+ Mg(OH)2 + Mg2++ 2OH-

H2O + MgCl2molecular eqn

ionic eqn

net ionic eqn

Mg(OH)2 + HCl

H2O + Mg2+ + Cl-

22

Mg(OH)2+ 2H++ 2Cl-2 H2O + Mg2+ +2Cl-

Mg(OH)2(s) +2 H+(aq) 2 H2O(l) + Mg2+(aq)

Acid/Base reactions

neutralization reactions products are not acidsbases

H+

OH-

equivalence point [H+] = [OH-]

mol H+

L= mol OH-

L

What volume of 0.100 M HCl is needed to neutralize 25.00 mL of 0.350 M NaOH

0.350 mol NaOHL

25.00 x 10-3 L = 8.75 x 10-3 mol NaOH

8.75 x 10-3 mol HCl0.100 mol HCl

L = 0.0875 L= 87.5 mL HCl

H2O

(x) (x)

A 2.2 g sample of an unknown acid, HA, is dissolved in 1.0 L of water.A titration required 25.0 mL of 0.500 M NaOH to react completely. What is the molecular weight of the unknown?

g HA 2.2 g HA

mol H+= mol OH-

0.500 mol NaOH

= 0.0125 mol OH-

0.0125 mol H+ =

2.2 g0.0125 mol

= 176 g/molmol HA

mol HA = mol H+

0.025 LL