Common Types of Reactions

Combination Rxns Between non-metals to give a molecular product

Between metal and non-metal to yield an ionic product

Between compounds

N2(g) + O2 (g) 2NO(g)

4Al(s) + 3O2 (g) 2Al2O3(s)

NH3(g) + HCl(g) NH4Cl(s)

(Al3+, O2-)

Decomposition Rxns

CuSO4.5H2O(s) CuSO4(s) + 5H2O(g)

MgCO3(s) MgO(s) + CO2(g)

Single Replacement Rxns

Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)

Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)

Double Replacement (Metathesis) Rxns

Precipitation Reactions

Acid-Base (Neutralization) Reactions

HNO3(aq) + NaOH(aq) H2O(l) + NaNO3(aq) acid base salt

Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)yellow solid

Acid-Base (Neutralization) Rxns

Oxidation-Reduction(Redox, Electron Transfer) Rxns

Precipitation Rxns

HNO3(aq) + NaOH(aq) H2O(l) + NaNO3(aq)

Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)

Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)

More Than One Way to Categorize

More About Acids and Bases... Acids

Taste sour (vinegar, lemon juice) Turn litmus red React with bases to make H2O React with many metals to make H2

React with carbonates to make CO2 and H2O

Bases Taste bitter Turn litmus blue React with acids to make water Feel slippery

The Arrhenius View

Acid - yields H+ when added to water HCl(g) + H2O(l) H+(aq) + Cl- (aq)

unbalanced

Base - yields OH- when added to water NaOH(s) + H2O(l) Na+(aq) + OH-(aq)

unbalanced

Arrhenius View of Neutralization

acid + base a salt + water

HCl (aq) + NaOH (aq) NaCl (aq) + H2O

The Brønsted View More general approach, not limited to water

Brønsted acid = H+ donor Brønsted base = H+ acceptor

Neutralization = “proton” (H+) transfer

Why is HCl a Brønsted Acid?

hydronium ion, H3O+

acidbase

Why is Ammonia a Brønsted Base?

Redoxe- transfer rxns

Oxidation-Reduction

2Fe (s) + 3Cl2 (g) 2FeCl3 (s)Fe3+, Cl-

Fe is oxidized (loses e-): Fe Fe3+ + 3e-

Cl2 is reduced (gains e-): Cl2 + 2e- 2Cl-

reducing agent (supplier of e-): Feoxidizing agent (acceptor of e-): Cl2

Adding Half Rxns Yields Overall Rxn

3Cl2 + 6e- 6Cl-reduction

2Fe 2Fe3+ + 6e-oxidation

2Fe + 3Cl2 2FeCl3 overall

Problem: What is the oxidizing agent when copper reacts with silver nitrate to form silver and copper(II) nitrate?

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

Ag+ is the oxidizing agent (consumes electrons from Cu)

Ag+ + 1e- Ag

Cu Cu2+ + 2e-

Problem: Is Cl reduced or oxidized when KClO3 decomposes?

2KClO3 2KCl + 3O2

?

Tracking e- Transfers

Oxidation State (Oxidation Number):The charge an element carries either alone or when

combined with other elements in a compound.

oxidation: O# goes upreduction: O# goes down

change in O# tells whether ox or red occurs

Simple Oxidation Number Rules

1. Free element O# = zero.Fe, Cl2, Na, Pb, H2, O2, P4 = 0

2. In monatomic ions, the O# = ion charge

Li+, Li = +1; Fe3+, Fe = +3; O2-, O = -2

3. Certain elements have same O# in ~all their compounds.

O usually -2, H usually +1 ...

4. (O# in cmpd) = overall charge of cmpd/ion.

More extensive rules are in text...

Problem: Is Cl reduced or oxidized when KClO3 decomposes ?

2KClO3 2KCl + 3O2

2KClO3 2KCl + 3O2

+1 -2 +1 -1 0+5Oxidation number drops (+5 to -1), so Cl is reduced.

1 potassium + 1 chlorine + 3 oxygens = 0 charge on KClO3

1(+1) + 1(?) + 3(-2) = 0

? = +5

HCO3-

1(+1) + 1(?) + 3x(-2) = -1

? = O# of C = +4

Problem: What are the oxidation numbers of all the elements in HCO3

- ?

O = -2

H = +1O#’s according to rules

C = ? no simple rule

1 hydrogen + 1 carbon + 3 oxygens = -1 charge anion

The Activity Series for Metals

Not important to memorize any of this. You’ll see it

again next semester.

Net Ionic Equations

To Describe Pptn and A-B Rxns

Problem: Pb(NO3)2 and NaCl ?

NaCl solution: contains Na+(aq) + Cl-(aq)

Pb(NO3)2 solution: contains Pb2+(aq) + NO3

-(aq)

How do we know ions are separated?

Problem: Pb(NO3)2 and NaCl ?

New Combinations?

Na+ with NO3-

NaNO3 is a strong electrolyte ions stay separated Represent as “NaNO3(aq)” or “Na+(aq) + NO3

- (aq)”

Pb2+ with Cl- PbCl2 is a weak electrolyte ions mostly together

Represent as “PbCl2(s)”

Ionic equation shows ions in correct state

Net ionic equation excludes spectator ions

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

--> PbCl2(s) + 2Na+ (aq) + 2NO3-(aq)

Pb2+(aq) + 2Cl-(aq) --> PbCl2(s)

Problem: Pb(NO3)2 and NaCl ?

Summary

Whole formula equation

Ionic equation

Net ionic equationPb2+(aq) + 2Cl-(aq) PbCl2(s)

2NaCl(aq) + Pb(NO3)2(aq) PbCl2(s) + 2NaNO3(aq)

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

PbCl2(s) + 2Na+ (aq) + 2NO3-(aq)

Problem: Write the net ionic equation for the reaction of sodium hydroxide and acetic acid in water.

wholeformula

ionic eqn

net ionic eqn

NaOH(aq) + HC2H3O2(aq) NaC2H3O2(aq) + H2O(l)

OH- + HC2H3O2 C2H3O2

- + H2O (l)

Na+ + OH-

+ HC2H3O2 Na+ + C2H3O2- + H2O

strong electrolyte

weak electrolyte

strong electrolyte

weak/non- electrolyte

wholeformula

ionic eqn

net ionic eqn

Problem: Write the net ionic equation for the reaction of sodium hydroxide and acetic acid in water.

Ca2+ + CO32- CaCO3

NH3 + H+ NH4+

Zn + 2HCl ZnCl2 + H2

Ca + F2 CaF2

Precipitation

Acid-Base

Redox (Single Displacement)

Redox (Combination)

Problem: Classify the following reactions.