Steps for Balancing Equations 1.Write the skeleton equation Use arrows, +/- & physical states of matter 2. Count the atoms of the reactants 3. Count the.

Steps for Balancing Equations

1.Write the skeleton equation Use arrows, +/- & physical states of matter

2. Count the atoms of the reactants3. Count the atoms of the products

4. Change the coefficients to make the number of atoms of each element equal on both sides of the equation

5. Write the coefficients in their lowest possible ratio

NEVER, NEVER CHANGE THE

SUBSCRIPT

Count the reactants & products

Balance the H & O atoms with coefficients for the reactants to = the

products

Add the physical states of the elements

Now you have a happy equation

A chemical reaction in which 2 or more reactants produce 1 product

General form A + B AB

In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make one product, a fat bird.

Examples

-2Na + Cl2 2NaCL

- 2Mg + O2 2MgO

- 4Al + 3O2 2Al2O3

- H20 + SO3 H2SO4 (this is one cause of acid rain)

- H20 +CO2 H2CO3 (this is why rainwater is naturally acidic)

- H2O + MgO Mg(OH)2

Special CASE “Scenarios” for these RXN’s

Metallic oxide + Water Base Na2O + H2O 2NaOH

Non-Metallic oxide + Water Acid

SO3 + H2O H2SO4

Special CASE “Scenarios” for these RXN’s

Metallic oxide + CO2 Metal carbonate

Metal chloride + Oxygen Metal chlorate

CaO + CO2 CaCO3

2KCl + 3O2 2KClO3

A chemical reaction where 1 compound, breaks apart into 2 or more

simpler productsGeneral form AB A + B

In this cartoon the egg (the reactant), which contained the turtle at one time, now has opened and the turtle (product) and egg shell (product) are now two separate substances.

Examples

- 2 H2O 2H2 + O2

- 2HgO 2Hg + O2

- 2Ag2O 4Ag + O2

- CaCO3 CaO + CO2

- H2CO3 H2O + CO2 -Decomposition reactions often require an

energy source:

Heat

Light

Electricity

Special CASE “Scenarios” for these RXN’s

Heating an acid non metallic oxide + water

Heating a carbonate oxide + CO2

Heating a base metallic oxide + water

Heating a metal chlorate chloride + O2

Heating a metallic oxide Metal + O2

These are just the reverse of their synthesis RXN’s

Heating a sulfite Metal oxide + SO2

A reaction in which atoms of one element replace the atoms of another element that

is part of a compound

Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants trades places and is in a different

place among the products

2. Anions replace Anions

1. Cations replace Cations

General Form AB + C CB + A

C would be the cation/metal and so replaced A, which would have to be a cation

General Form DE + F DF + E

F would be the anion/non-metal and so replaced E, which would have to be a anion

Examples:

a.Cu + AgNO3 Cu(NO3)2 + Ag

Cation replaces Cation

b.NaI + Cl2 NaCl + I2

Anion replaces Anion

Special situations for SR RXN’s1. Activity Series

Definition

A list of metal/cations in order of decreasing reactivity

Used to determine if one metal can replace another in a RXN

The higher its position on chart the more metals it can replaceEx: sodium will replace aluminum

The lower its position on the chart the less metals it can replaceEx: zinc will not replace magnesium

3. Halogens The halogens also have a series;

As you go down group 17 they decrease in reactivityEx: Chlorine cannot replace fluorine but it can replace bromine

Special situations for SR RXN’s2. Water for writing RXN’s it may be useful to write water

as H(OH). Why?

Special situations for SR RXN’s

Do the following reactions occur? Explain.

Zn + H2SO4 H2 + ZnSO4

Sn + 2NaNO3 Sn(NO3)2 + 2Na

2NaCl + F2 2NaF + Cl2

CaCl2 + I2 CaI2 + Cl2

A reaction where there is an exchange of cations between 2 ionic compounds

Notice how the first guy exchanged hats with the second guy, so they are

both wearing each other's hat.

General FormAB + CD AD + CB

** Make sure of cation and anion placement

Ex: BaCl2 + K2CO3 BaCO3 + 2KCl

3KOH + H3PO4 3H(OH) + K3PO4

“Driving Forces” in double replacement RXN’s

One of three things must form for these RXN’s to occur

1. A molecular compound like water forms

2. A gas forms that bubbles out i.e. (H2, CO2, H2S, CO, etc.)

3. A precipitate forms

“Driving Forces” allow a RXN to take placeUse your net ionic equation to see if one of the following are formed

How do you know if something is a precipitate?

1. It is insoluble or slightly soluble in water 2. Check your solubility chart

Examples: will these RXN’s occur? Explain

BaCl2AgCl

Ca3(PO4)2

NaNO3

Soluble….NR

Insoluble….YesInsoluble….Yes

Soluble….NR

Examples: will these RXN’s occur?

FeS(s) + HCl(aq) FeCl2(aq) + H2S ↑

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

FeCl3 (aq) + Al(NO3)3 (aq) Fe(NO3)3 (aq) + AlCl3 (aq)

Yes

Yes

No…soluble …no “driving force” present

Definition:Oxygen reacts with another substance often producing energy in the form of heat and light

Types:

1. Complete combustion

Hydrocarbons combine with oxygen to produce carbon dioxide and water

Definition:

If sufficient oxygen is present to burn completely

General form: CxHy + O2 CO2 + H2O

Definition:

2. Incomplete combustion

Insufficient oxygen is present to burn completely

Hydrocarbons combine with oxygen to produce poisonous carbon monoxide and solid elemental carbon as well as carbon dioxide and water

Examples:

Extra “Special” RXN’s

• Reactive metals and water (SR)

• Group 1 and 2 metals react to form a metal hydroxide and hydrogen gas

• Acid and a Base

• React to form a salt (ionic compound composed of the anion of the acid and the cation of the base) and water

Aqueous SLN

• When two (aq) solutions that contain ions as solutes combine….

• The ions may react with one another

• The H20 molecules don’t usually react

• The three types of products can form aka “driving forces” …. Gas, water, or precip

• Chemical equations do not always show all that happens in a RXN

• Solutions are composed of

• Solute

• Solvent

• Aqueous SLN

• Is a sln in which the solvent is water

Net Ionic Equations

Net Ionic Equations

• Substances that are ions in a solution and are written as such

• These equations show all of the particles in a solution as they “really” exist

• Some ions are in both the RXT & PROD, these are called…

• SPECTATOR IONS

Net Ionic Equations

• SPECTATOR IONS - dissociation only occurs if it is in an aqueous solution

• S, L, G are not ions see your solubility chart

Net Ionic Equations

• Regular equation• 2NaOH (aq) + CuCl2 (aq) 2NaCl (aq) + Cu(OH)2(s)

• Ionic equation• 2Na+ (aq) + 2OH- (aq) + Cu+2(aq) + 2Cl- (aq) 2Na+

(aq) + 2Cl- (aq) + Cu(OH)2 (s)

Net Ionic Equations

• Net Ionic equation

• 2OH- (aq) + Cu+2(aq) Cu(OH)2 (s)

• Net ionic equation is formed when all of the spectator ions are cancelled