chapter 6 chemical reactions and equations. what are diatoms? 7 gases must exist as diatoms (two...

Chapter 6Chapter 6

Chemical Reactions and Chemical Reactions and EquationsEquations

What are Diatoms?What are Diatoms?7 gases must exist as diatoms

(two atoms)This means those atoms will

NEVER be found alone.

They are H2O2F2I2N2Br2Cl2◦Also known as the HOFINBrCl Twins!

How Do we write a chemical How Do we write a chemical formula?formula?We use what was earned in

chapter 5 to translate a word into a chemical formula

Copper II Chloride becomes CuCl2

Dinitrogen Monoxide becomes N2O

Example 1Example 1

Write the following statement into a chemical formula:

Mercury II Oxide decomposes into Merucury and Oxygen

Example 2Example 2

Write the following statement into a chemical formula:

Aluminum is dropped into a beaker of hydrochloric acid (HCl). The reaction yields Aluminum Chloride and Hydrogen Gas.

Chemical FormulasChemical Formulas2AgNO3(aq) + Cu(s) --> Cu(NO3)2(aq) +

2Ag(aq)

What do all of the things in parentheses mean?

Symbols in Chemical Symbols in Chemical ReactionsReactions(s)

(l)

(g)

(aq)

Solid

Liquid

Gas

Aqueous (dissolves in water)

Products and ReactantsProducts and ReactantsProducts are After the Arrow

Reactants are Before the arrow

They MUST Equal each other

◦Reactants -- > Products

Is this Balanced?Is this Balanced?H2 + O2--> H2O2 2

+

Balance the equationBalance the equation

CS2 + Cl2 --> CCl4 + S2Cl21 13 1

Balance: Balance: Sodium + Water -->Sodium + Water -->Sodium Hydroxide + HydrogenSodium Hydroxide + Hydrogen

Na + H2O --> NaOH + H22 22 1

CombinationCombinationTwo elements combine to make a

single compoundA + B AB

Magnesium Oxide◦Mg + O2 MgO

CombinationCombinationTwo elements combine to make a

single compoundA + B AB

Magnesium Oxide◦2Mg + O2 2MgO

DecompositionDecompositionOne compound forms two

elementsAB A + B

Mercury Oxide◦HgO(g) Hg(l) + O2(g)

DecompositionDecompositionOne compound forms two

elementsAB A + B

Mercury Oxide◦2HgO(g) 2Hg(l) + O2(g)

Single-ReplacementSingle-ReplacementAn element replaces another

element from a compound in an aqueous solution

A + BC AC + B

Aluminum in HCl◦Al(s) + HCl(aq) AlCl3(aq) + H2(g)

Single-ReplacementSingle-ReplacementAn element replaces another

element from a compound in an aqueous solution

A + BC AC + B

Aluminum in HCl◦2Al(s) + 6HCl(aq) 2AlCl3(aq) + 3H2(g)

Double-ReplacementDouble-ReplacementTwo ionic compounds switch cationsAB + CD AD + CB

Potassium Carbonate and Barium Chloride◦K2CO3(aq) + BaCl2(aq) KCl(aq) +

BaCO3(s)

Double-ReplacementDouble-ReplacementTwo ionic compounds switch cationsAB + CD AD + BC

Potassium Carbonate and Barium Chloride◦K2CO3(aq) + BaCl2(aq) 2KCl(aq) +

BaCO3(s)

CombustionCombustionA fuel and oxygen always give CO2, H20,

and HEATCxHy + (x + y/4)O2 xCO2 + (y/2)H2O +

HEAT

Methane Burning◦CH4(g) + O2(g) CO2(g) + H2O(g) + Heat

CombustionCombustionA fuel and oxygen always give CO2, H20,

and HEATCxHy + (x + y/4)O2 xCO2 + (y/2)H2O +

HEAT

Metane Burning◦CH4(g) + 2O2(g) CO2(g) + 2H2O(g) + Heat

Reaction RatesReaction RatesAll reaction occur at a certain

rate of time

Four factors can affect how fast or slow a reaction can go

1. Temperature1. Temperature

Usually, increasing the temperature increases the reaction rate.

Increases the kinetic energy of particles when they collide

2. Concentration 2. Concentration (Molarity)(Molarity)

More particles reacting means more of a chance for a reaction to occur

A higher concentration means a higher reaction rate

3. Particle Size3. Particle Size

The smaller the particle, the higher the surface area.

Higher surface area means something has a better chance to react.

4. Catalyst4. Catalyst

The addition of a catalyst increases a reaction by lowering the activation energy without using up the catalyst

Activation Energy is the energy needed in order for a reaction to occur