Download Chemical Equation

Advanced Physical Science B
Chemistry in Review:
The Ions
Chemical Formulas
Chemical Equations
Stoichiometry
The Ions
Ions
• In general ions are formed from that lose or
gain enough electrons to gain a full octet in
their valence shell.
• Elements that lose electrons become a
positive CATION.
• Elements that gain electrons become a
negative ANION.
Oxidation Numbers
Monatomic Cations
• Monatomic- one type of atom.
• Most metals make monatomic cations, with a
positive charge.
• Usually the group number indicates the oxidation
number of the elements in that group.
• The cation simply has the same name as the
element.
• Transition Metals have multiple oxidation
numbers.
Elements with Multiple Charge
•
•
•
•
•
Cu+1, Cu+2
Fe+2, Fe+3
Pb+2, Pb+4
Sn+2, Sn+4
Hg2+2, Hg+2
•
•
•
•
•
Cuprous, cupric
Ferrous, ferric
Plumbous, plumbic
Stannous, stannic
Mercurous, mercurric
High -ic and Low -ous!
Monatomic Anion
• Monatomic- single type of atom.
• Anions are usually made from Nonmetals, groups
15, 16, and 17. They gain electrons in their
Valence.
• All Anions end with a suffix.
• Most monatomic anions end with a “-ide”.
Polyatomic Cations
• Polyatomic- more than one atom.
• There just a few polyatomic cations.
• NH4+, ammonium
• Hg2+2, mercury(I)
Polyatomic Anions
• Polyatomic anions have more than one atom.
• A nonmetal plus oxygen or oxygen and hydrogen.
– Sometimes called an “oxyanion.”
• Anions end with a suffix.
– Most end with “-ate”
– Polyatomic anions with less oxygens end with “-ite”
• “ite” anions usually have one less oxygen then
“ate” anions.
• “ate” ate the “ite”!
Chemical Formulas
The building blocks.
Symbols and Formulas
• Names of Elements - 109 elements, >10
million known compounds
 Compounds are represented by formulas
combining chemical symbols and numeric
subscripts.
 Some elements are named for their properties.
Nitrogen-“niter forming”
Plumbic (lead)-shiny
 Some elements are named for their place of origin.
Symbols and Formulas (cont.2)
 Some elements are named for the minerals they
are found in.
 Tungsten-Swedish name for “heavy stone”
 Some elements are named in honor of a person.
• Symbols for the elements
 One or two letters, the first letter is capitalized
 In 1813, JJ Berzelius, a Swedish chemist
developed the modern symbols for designated
elements.
Chemical Formulas
• Are a combination of symbols that represent
the composition of a compound.
• Molecular Compounds and Ionic
Compounds.
Ionic Compounds
• Are compounds composed of charged
particles.
• In general: the electrons are shared between
the ions. Metals tend to give up their
electrons to an incomplete nonmetal.
• All Ionic compounds are represented by
their empirical formulas. They are always
in the smallest whole number ratios.
Other Types of Molecules
• Diatomic Molecules:these 7 elements must
exist in nature paired with itself or other
elements.
–
–
–
–
Br2, Bromine
I2, Iodine
Cl2, Chlorine
F2, Fluorine
• “BrIClFOHN”
- O2, Oxygen
- H2, Hydrogen
- N2, Nitrogen
Other Types of Molecules (cont.2)
• Hydrates:Ionic Molecules attached to water
molecules.
• Organic Molecules:contains carbon as it’s
central element.
• Alloys: metals form these molecules where
atoms are held together by a “sea” of
electrons.
Predicting Formulas of Ionic
Compounds
• Write the symbols for the elements in the
compound
– Always write the CATION first.
• Determine the charge on each ion.
– Na+1=+1, O-2=-2
• From the charge on each ion use subscripts to
indicate the multiplier for the ions.
– The total positive must equal the total negative.
– The “total” charge of the compound must be zero.
– Ex. Na2O
Predicting Formulas of Ionic
Compounds (cont.2)
• When using subscripts for polyatomic ions,
the ion is placed in parentheses, and the
subscript is placed on the outside to indicate
“x” ion units.
– The subscript applies to all the elements in the
parentheses.
• If the subscript is “1”, it is understood and
not written.
– For monatomic ions no parentheses is used.
Naming Ionic Compounds
• Naming Binary Ionic Compounds:
 The cation is listed first, then the monatomic
anion.
 For stock names include the oxidation number of
the cation in parantheses.
 For traditional names use the “-ous” or “-ic” name
for the cation.
Naming Ionic Compounds (cont.2)
• Naming Ternary Ionic Compounds:
 Made up with a cation and a polyatomic anion.
 The suffix tells which anion.
 “-ate” for more oxygen's
 “-ite” for less oxygen's.
Chemical Equations
A chemical recipe
Types of Chemical Reactions
• There are 5 fundamental types of Chemical
Reactions.
–
–
–
–
–
Synthesis (Direct Combination)
Decomposition (Analysis)
Single Replacement
Double Replacement
Combustion
Synthesis(Direct Combination)
• “joining together”
– The general form of reaction:
•A + B
AB
• element+element
compound
• Two reactants
One product
Synthesis (cont.2)
QuickTime™ and a
Sorenson V ideo decompressor
are needed to see this picture.
O2 + 2NO
2NO2
Decomposition (Analysis)
• “breaking down”
– The general form of reaction:
• AB
A + B
• compound element + element
• One reactant
Two products
Decomposition (cont.2)
QuickTime™ and a
Sorenson V ideo decompressor
are needed to see this picture.
2NI3
N2 + 3I2
Single Replacement
• “Like ions must displace like ions”
– The general form of reaction:
• A + BC
AC + B
• element + compound
compound + element
• Two reactants
Two products
Single Replacement (cont.2)
QuickTime™ and a
Sorenson V ideo decompressor
are needed to see this picture.
Fe2O3 + 2Al
Al2O3 + 2Fe
Double Replacement
• “Exchanging ions”
– The general form of reaction:
• AC + BD
AD + BC
• compound+compound compound+compound
• Two reactants
Two products
Double Replacement (cont.2)
QuickTime™ and a
Sorenson V ideo decompressor
are needed to see this picture.
AgNO3 + NaCl
AgCl + NaNO3
Combustion
• Special form of a decomposition rxn.
• Burning hydrocarbons.
– Metabolism
– The general form of reaction:
• hydrocarbon + oxygen
CO2 + H2O
• Presence of oxygen in the form, O2
• Products are always CO2 and H2O
Combustion (cont.2)
QuickTime™ and a
Sorenson V ideo decompressor
are needed to see this picture.
2C8H18 + 17O2
18H2O + 8CO2
Special Considerations for
Replacement Reactions
• Single Replacement Reactions: follow the
“Activity Series” of elements.
–
–
–
–
Cations displace cations.
Anions displace anions.
Li+1 is the most reactive cation.
F-1 is the most reactive anion.
• Double Replacement Reactions: must show
evidence of a chemical reaction.
– “God Punishes Chemistry Teachers”
– Gas, Precipitate, Color change, Temperature change.
Atom Accounting
• Reactants-a starting substance in a chemical
reaction.
• Products-a substance produced in a
chemical reaction.
• Atoms in the reactants must equal the atoms
in the products.
Balancing Chemical Equations
• Do an “Atom Accounting”
– H2 + N2
NH3
H=2
N=2
– Li + Al2(SO4)3
Li=1
Al=2
S=3
O=12
H=3
N=1
Li2SO4 + Al
Li=2
Al=1
S=1
O=4
Balancing Basics
•
Rules for Balancing Chemical Equations:
1. Law of Conservations of Matter: “What goes
IN must come OUT”
Be sure the elements in the products are in the
reactants.
2. Make sure COMPOUNDS are good chemical
formulas.
Use subscripts to make formulas.
Balancing Basics (cont.2)
3. Balance the atoms on each side of the
equation using COEFFICIENTS.
Do NOT Touch the Subscripts!
4. Keep the coefficients in the lowest whole
numbered ratios.
•
•
•
Ex. 4H2 + 2O2
2H2O
Will be:
2H2 + O2
H2O
Balancing Basics (cont.3)
• Balance the equation:
– 3H2 + N2
2NH3
H=2 6
N=2
H=3 6
N=1 2
Balancing Basics (cont.4)
– Li + Al2(SO4)3
Li=1
Al=2
S=3
O=12
– 6Li + Al2(SO4)3
Li=1 6
Al=2
S=3
O=12
Li2SO4 + Al
Li=2
Al=1
S=1
O=4
3Li2SO4 + 2Al
Li=2 6
Al=1 2
S=1 3
O=4 12
Stoichiometry
Mathematical with chemical
equations.
Stoichiometry
•
•
A Chemical Equation gives information about
the relative relationship (ratio) between reactants
and products in a chemical reaction.
Coefficients of a balanced chemical equation
gives three pieces of quantitative information
about the reactants and the products.
1. The relative number of particles.
2. The relative number of moles.
3. The relative volume of a gas, at the same temperature
and pressure.
Stoichiometry (cont.2)
•
When a chemical equation is balanced, the
total mass of the reactants equals the total
mass of the products. (Law of
Conservation of Mass)
–
–
The coefficients DO NOT give relative ratios
of reactants to products by mass.
Must convert to MOLE or particles the
compare coefficients.
Stoichiometry (cont.3)
•
Organization is critical.
1. Balance the chemical equation, FIRST!
2. Determine the element/compounds that is
given and the element/compound that is
sought. Make a chart.
3. Place the information given in the problem
under the correct element/compound.
Extended Mole Map
–
Mixed Stoichiometric
Relationship
In general, this relationship holds:
1. All mixed relationship problems take 3 steps.
2. First, always balance the chemical equation and
organize the problem. Determine what is Given and
what if Sought.
3. Convert Given to moles, Change Given to Sought,
Convert from Sought moles to whatever units asked
for.
•
•
•
•
Remember:
If changing to/from mass: 1mol=Molar Mass
If changing to/from particles: 1mol=6.02x1023parts
If changing to/from volume(gases only): 1mol=22.4dm3 at
STP
Mixed Stoichiometric
Relationship (cont.2)
• MOLES RULE!!!
• In One DA Table:
Xunit,Sought = Given,units CF1 CF2 CF3
• Where:
• CF1=converts units Given to moles
• CF2=converts moles Given to moles Sought. The Mole
Bridge.
• CF3=converts moles Sought to units Sought.
Try this mass-mass problem:
•
Calculate the mass of oxygen produced if 2.50g
of potassium chlorate is completely decomposed
to give potassium chloride and oxygen.
1. Balance the Chemical Equation:
•
2KClO3
2KCl + 3O2
2. Determine the Given and the Sought:
•
•
Given: 2.50g KClO3
Sought: mass of O2 produced
3. Organize the appropriate information:
•
2.50g KClO3
Xg O2
In One Step
• Calculate the mass of oxygen produced if 2.50g of
potassium chlorate is completely decomposed to give
potassium chloride and oxygen..
• The balanced chemical equation:
•
•
2KClO3
2KCl + 3O2
XgSought =Givenmass 1molGiven
MolarMassGiven
•
Mole
MolarMassSought
Bridge
1mol Sought
XgO2 = 2.50gKClO3 1molKClO3 3O2
32gO2
123gKClO3 2KClO3 1molO2
= 9.76x10-1gO2
#2 Try this:
•
How much silver phosphate is produced if
10.0g of silver acetate reacts with sodium
phosphate?
1. Balance the Chemical Equation.
2. Organize the problem.
3. Use Three or One Step to solve the problem.
How much silver phosphate is
produced if 10.0g of silver acetate
reacts with sodium phosphate?
3AgC2H3O2+ Na3PO4
10.0gAgC2H3O2
Ag3PO4+ 3 NaC2H3O2
XgAg3PO4
XgAg3PO4=10.0gAgAce 1AgAce
1Ag3PO4 418.58gAg3PO4
166.92gAgAce 3AgAce 1Ag3PO4
X= 8.36gAg3PO4