2 x 1 mole 2 x 1 mole 1 x 1 mole

by numbers by volume

Chemical Methodsfor counting amountsfor counting amounts

Physcisal Methods

COUNTING

2 H2O 2 H2 + 1 O2

by weighing

by balanced reaction

1 mole any gas = 22.4 L @ 0°C,1atm

1 pr = 21 doz = 12

1 case = 12 or 24

1 hand = 5 fingers

1 foot = 12 inches

1 gummy bear = 1 gram1 penny = 1 gram1 proton = 1 amu1 neutron = 1 amu1 hydrogen-1 atom = 1 amu

1 carbon-12 atom = 12 amu

1 mole = 6.02x10+23

anything anything

Avogadro'snumber

1 mole carbon-12 = 12 grams carbon-12 exactly

(6.02x10+23

) (6.02x10+23

)

numbers to amountsby weighing

2 molecule 2 molecules 1 molecule

2 x A number 2 x A number 1 x A number

2 x 6.02x10+23 2 x 6.02x10

+23 1 x 6.02x10+23

multiply through by A number

A number equals Avogadro's #

Avogadro's # equals 1 mole

2 x 18 grams 2 x 2 grams 1 x 32 grams

count by weighing

H2O H2 O2per

1 moleper

1 moleper

1 moleO2H2H2O

molar massesdefined

the eletrolysis of 36 grams of water will produce 4 grams of hydrogen and 32 grams oxygen

Supplemental packet page 117

2 x 1 mole 2 x 1 mole 1 x 1 mole

Chemical Methodsfor counting amounts

2 H2O 2 H2 + 1 O2

by balanced reaction

2 molecule 2 molecules 1 molecule

2 x A number 2 x A number 1 x A number

2 x 6.02x10+23 2 x 6.02x10

+23 1 x 6.02x10+23

multiply through by A number

A number equals Avogadro's #

Avogadro's # equals 1 mole

2 x 18 grams 2 x 2 grams 1 x 32 grams

count by weighing

H2O H2 O2per

1 moleper

1 moleper

1 moleO2H2H2O

This is a chemical recipe forthe decomposition of waterby electrolysis.

productsreactants

What did John Dalton in 1808 have to say about chemical reactions?

1. Chemical reactions involve just the simple rearrangement of atoms.

2. Atoms are conserved in a chemical reaction.In other words, atoms are not created nor destroyed in chemical reaction.

Is this true for the decomposition of water by electrolysis?

2 H2O 2 H2 + 1 O2

Write the following opposite supplemental packet page 106

2 H2O 2 H2 + 1 O2

1. Chemical reactions involve just the simple rearrangement of atoms.

2. Atoms are conserved in a chemical reaction.In other words, atoms are not created nor destroyed in chemical reaction.

This ture for the below decomposition of water by electrolysis.

H HO

OHH

O

O

H H

HH

4 hydrogen atoms 4 hydrogen atoms

2 oxygen atoms 2 oxygen atoms

Let’s see if John Dalton had assumed correctly.

2 H2O 2 H2 + 1 O2

by balanced reaction

2 molecule 2 molecules 1 molecule

multiply through by A number

2 x A number 2 x A number 1 x A number

A number equals Avogadro's #

2 x 6.02x10+23 2 x 6.02x10

+23 1 x 6.02x10+23

Avogadro's # equals 1 mole

2 x 1 mole 2 x 1 mole 1 x 1 mole

count by weighing

2 x 18 grams 2 x 2 grams 1 x 32 gramsH2O H2 O2per

1 moleper

1 moleper

1 moleO2H2H2O

36 grams H2O produces 4 grams H2 and 32 grams O2

Stoichiometry supplemental packet page 117

2 H2O 2 H2 + 1 O2

by balanced reaction

2 molecule 2 molecules 1 molecule

multiply through by A number

2 x A number 2 x A number 1 x A number

A number equals Avogadro's #

2 x 6.02x10+23 2 x 6.02x10

+23 1 x 6.02x10+23

Avogadro's # equals 1 mole

2 x 1 mole 2 x 1 mole 1 x 1 mole

count by weighing

2 x 18 grams 2 x 2 grams 1 x 32 gramsH2O H2 O2per

1 moleper

1 moleper

1 moleO2H2H2O

⊕

9 voltbattery

OOH H

HH

H HOO

HH

9 voltbattery

(source of electrons)

#

#

H H

O

O

HH

ElectrolysisDr.Gergens - SD Mesa College

Stoichiometry supplemental packet page 118

Reduction is Gain, RIG

2 H2O 2 H2 + 1 O2(l) (g) (g)

0 0

2H+ + 2e- H20

The battery supplies those electrons⊕

9 voltbattery

Remember hydrogen ions’s favorite charge inits combined state is:

H+

⊕

9 voltbattery

2 H2O 2 H2 + 1 O2(l) (g) (g)

Then what happened the oxygen atom in water?

0 0

So oxide ion must have lost electrons

O2- O0 + 2e- Lost electrons in the electrolysis are attractedTo the positive ca hode⊕

Oxidation is loss of electrons, OIL

Remember oxygen ion’s favorite charge inits combined state is:

O2-

2-

O2- O0 + 2e- 2H+ + 2e- H2

0 Oxidation is Loss, OIL

Reduction is Gain, RIG

REDOX,is about the exchange of electrons.

Summary:

21 H2 + 1 O21 H2O

2 H2O 2 H2 + 1 O2(l) (g) (g)

0 0

Take the summation of both half-reactions affords the overall rxn below

Equilibrium

off-balanced(unequal)

reactant to product Equilibrium

balance Precipitation saturation

(solid formation)

gas formation

Up & DownReflux

likeacid reflux

(heart burn)

Supplemental packet page 106

The chemical equation is the shorthand notation for a chemical reaction.

ProductsReactantsreact to produce

Law of Conservation of Mass - Matter cannot be gained or lost in the process of a chemicalreaction. The law of conservation of mass states that we must have a balanced equation.List five factors involved in the construction of an equation or "chemical recipe."1.The identity of products and reactants must be specified.

2.Reactants are written to the left of the reaction arrow (---->) and products to the right.

3.The physical state of reactants and products is shown is parentheses;

(s), (l), (g), (aq). Recall (aq) means aquesous solutoins (solute + solvent)

4.The symbol Δ .over the reaction arrow means that heat energy is necessary for the reaction to occur

5. .The equation must be balanced

Supplemental packet page 106

Steps for balancing a chemical equation

Step 1: Count the number of atoms of each element on both the product and reactant side.Step 2: Determine which atoms are not balanced.Step 3: Balance one atom at a time, using coefficients. Start with atoms that appear

only once in the reactants and only once in the products. Usually leaveHydrogen atoms followed by Oxygen atoms until last.

Step 4: After you believe that you have successfully balanced the equation, repeat Step1, to be certain that mass conservation has been achieved.

Note:

Na2Cl2 )XDO NOT Change subscripts in a molecular formula (i.e., 2 NaCl

Don’t do this!!!!

Supplemental packet page 106

2 Mg + 1 O2 2 MgO 2 21

2 Mg + 1 O2 2 MgO

In balancing, we would like the lowest whole number molar ratio. Where the number out in front is called a molar coefficient.

Write this into our notes

2 Mg + 1 O2 2 MgO

2 Mg + 1 O2 2 MgO 1 12 •

But what if an individual balanced the magnesium first?

12

The reaction is balanced, BUT there is a fractional molar coefficient.We must remove the fraction by multiplying through by 2.

2 1 2

2 • 1 2 • 12

2 • 1

In my opinion, the following is the easiest way to balance, if you:1) always balance oxygens last;

2) then multiply by factor of 2, to remove any fractional molar coefficient that might be present in the balanced reaction.

32

1 Fe2O3 2 Fe + O22 132

32

1 Fe2O3 2 Fe + O2

2 •

4 3 2

2 • 2 2 • 32

2 • 1

Note: We are going for the lowest whole numberMolar coefficient ratio

2 Mg + 1 O2 2 MgO

Finally, name the compounds and give physical states.

(s)

magnesium metalsolid

(g)

oxygengas

(s)

magnesium oxidesolid ionic salt

32

1 Fe2O3 2 Fe + O24 3 2(s)

iron metalsolid

(g)

oxygengas

(s)

iron (III) oxidesolid TM ionic salt

1CO2 + 2H2O 1CH4 + 2O2 Always balance oxygens last

1 1

1 • O2 + 2 • 1O

? • O2 = 4

2?2

2 + 2 = 4

Combustion of methane gas

? • O2 = 7

72

2CO2 + 3H2O 1C2H6 + O2

72

2CO2 + 3H2O 1C2H6 + O2 Always balance oxygens last

1 2

2 • O2 + 3 • 1O

4 + 3 = 7

3?722

2 • 1 2 • 72

2 • 2 2 • 3

2 7 4 6

Combustion of ethane gas

1CO2 + 2H2O 1CH4O + 3O2 Always balance oxygens last

1 1

1 • O2 + 2 • 1O

2 + 2 = 4

2?

1 • O + ? • O2 = 4

1 + ? • 2 = 4 Now solve for “?”

? • 2 = 3-1 -1 Substract one from each side

23

? =23

2 2 Divide each side by 2

Combustion of methanol liquid

1CO2 + 2H2O 1CH4 + 2O2O

1CO2 + 2H2O 1CH4O + 3O21 1 2?232

2 x 1 2 x 32

2 x 1 2 x 2

2 3 2 4

Combustion of methanol liquid

6CO2 + 6H2O1C6H12O6 + 6O2 Now balance the combustion of glucose (blood sugar)

Always balance oxygens last

1 6

1 • O2 + 6 • 1O

1•O6 + ? • O2 = 18

6?6

12 + 6 = 18

6 + ? • 2 = 18 Now solve for “?”

? • 2 = 12

-6 -6 Substract 6 from each side

? = 6

2 2 Divide each side by 2

Combination - Synthesis - PHOTOSYNTHESIS

6 16 6CO2 + H2O C6H12O6 + O2chlorophyllcatalyst

C2H6O + O2 CO2 + H2O

CH2O + O2 CO2 + H2O

combustion

1 2 33

1 1 11

CH4O + O2 CO2 + H2O2 2 43

2x CH4O + O2 CO2 + H2O1 1 23__

2

Don’t leave as a fraction, multiply through by 2Combustion of methanol, CH4O

Combustion of ethanol, C2H4O

Combustion of formaldehyde, CH2O

What reactant was oxidized? What reactant was reduced?

C 4+ O 2–O

2–

Ionic salt transfer reactions in aqueous solution

Ionic salt solubility in water

All group I salts soluble, Li,Na,KAll nitrate salts solubleAll ammonium salts soluble,NH4

+

Driving forces for ion transfer, a force that makes the reaction go.

Physical state formations:If a solid formsIf a liquid formsIf a gas forms

Evidence for chemical change, ∆Color change (tricky)Heat evolved (tricky)

precipitation saturation (solids)If a liquid forms (heat evolved)If a gas forms (bubbles, odor)

A+B- (aq) + C+D- (aq) AD(?) + BC(?)

you’ll need to determine statebased on some rules

Ionic salt transfer reactions in aqueous solutionA+B- (aq) + C+D- (aq) AD(?) + BC(?)

Common sense tells us to mix ionic solutions in order to have an reaction to occur. (we are not going to mix for the sake of mixing)

Use of common sense tells us that,An acids mixed with a base (antacid) causes a neutralization.

H+A- (aq) + M+OH- (aq) H2O (l) + MA(?)Use of common sense tells us that,An acids mixed with carbonate (HCO3

-) produces CO2 water and salt

H+A- (aq) + NaHCO3 (aq) H2O(l) + NaA(aq)

CO2 (g)

A+B- (aq) + C+D- (aq) AD(?) + BC(?)

silver (I) cloride + sodium nitratesilver (I) nitrate + sodium chloride silver (I) cloride + sodium nitratesilver (I) nitrate + sodium chloride Say the product namessilver (I) nitrate + sodium chloride silver (I) chloride + sodium nitrateNow write the ions associated with each substance

Ag+ (NO3)– Na+ Cl- Ag+ (NO3)–Na+Cl-

Now write formuals for the products

AgCl + NaNO3

Identify physical state in aqueous solution

Solubility rules need to be applied.

(s) (aq)

monatomic ions oxy ions, XO–

suffix -atessuffix -ides

isoelectronic chargesPO4

3- SO4

2- ClO4

1-

BO33-

CO32-

NO3-

C4±

N-3 O

2- F

1-

P-3 S

2- Cl

1-

MUST learn X— charges!!!

carbide ion

X- charges

nitride ionoxide ionfluoride

phosphide ionsulfide ionchloride ion

phosphate ionsulfate ionperchlorate ion

borate ioncarbonate ionnitrate ion

Feo Fe 2+ + 2e- OxidationOIL

1 1

Fe(s) + Cl2(g) FeCl2 (s) 1 11

Combination - Synthesis (the REDOX process defined)

Analyzing the half reactions

Cl2o + 2e- 2Cl – Reduction

RIG

Fe 2+Cl –

Cl –

iron (II) chloridechlorine gasiron metal forms>plus

Feo Fe 2+ + 2e- OxidationOIL

Cl2o + 2e- 2Cl – Reduction

RIG

1 1

11

Fe(s) + Cl2(g) FeCl2 (s) 1 11

Combination - Synthesis (the REDOX process defined)

Analyzing the half reactions

Fe 2+Cl –

Cl –

iron (II) chloridechlorine gasiron metal forms

combining both half reactions

1 Fe(s) + 1 Cl2(g) 1 FeCl2 (s)

the electrons on the reactant side cancel the electrons on the product side

2 Mg + 1 O2 2 MgO

What reactant was oxidized?

(s)

magnesium metalsolid

(g)

oxygengas

(s)

magnesium oxidesolid ionic salt

What reactant was reduced?

Mg O O2O Mg 2+ O

2–

Mgo lost electrons

Oxygen gained electrons

What reactant was oxidized?

32

1 Fe2O3 2 Fe + O24 3 2(s)

iron metalsolid

(g)

oxygengas

(s)

iron (III) oxidesolid TM ionic salt

What reactant was reduced?

Fe 3+ O 2–

Fe 3+ O 2–

O 2–

Fe O

Iron metal lost electrons

O2O

Oxygen gained electrons

Combustion of methanol in PLASTIC BOTTLE

REDOX MID-TERM

Fe + Cl2 FeCl21 11

2 H2O 2 H2 + 1 O2

H HO

OHH

O

O

H H

HH

4 hydrogen atoms 4 hydrogen atoms

2 oxygen atoms 2 oxygen atoms

SOLUBILITY in aqueous solutions

BATTERY DEMO

2 x 1 mole 2 x 1 mole 1 x 1 mole

by numbers by volume

Chemical Methodsfor counting amountsfor counting amounts

Physcisal Methods

COUNTING

2 H2O 2 H2 + 1 O2

by weighing

by balanced reaction

1 mole any gas = 22.4 L @ 0°C,1atm

1 pr = 21 doz = 12

1 case = 12 or 24

1 hand = 5 fingers

1 foot = 12 inches

1 gummy bear = 1 gram1 penny = 1 gram1 proton = 1 amu1 neutron = 1 amu1 hydrogen-1 atom = 1 amu

1 carbon-12 atom = 12 amu

1 mole = 6.02x10+23

anything anything

Avogadro'snumber

1 mole carbon-12 = 12 grams carbon-12 exactly

(6.02x10+23

) (6.02x10+23

)

numbers to amountsby weighing

2 molecule 2 molecules 1 molecule

2 x A number 2 x A number 1 x A number

2 x 6.02x10+23 2 x 6.02x10

+23 1 x 6.02x10+23

multiply through by A number

A number equals Avogadro's #

Avogadro's # equals 1 mole

2 x 18 grams 2 x 2 grams 1 x 32 grams

count by weighing

H2O H2 O2per

1 moleper

1 moleper

1 moleO2H2H2O

molar massesdefined

the eletrolysis of 36 grams of water will produce 4 grams of hydrogen and 32 grams oxygen