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Warm-Up
predict the Molecular Geometry
for each
•PBr3
+
•XeF5
•ClF4+
UNIT 4 – What’s in a name
Balancing Chemical Equations
•In Balanced Chemical Equations, each side of
the equation has the same number of atoms
of each element
•Coefficients are used to balance chemical
equations
Rules for Balancing Equations
•1. Determine the correct formulas for
the reactants and products
•2. Write the formulas for the reactants
on the left side of the arrow. Write the
formulas for the products on the right
side of the arrow
Rules Continued
•3. Count the number of atoms of
each element present on both sides
of the equation
•4. Balance the elements one at a
time by placing coefficients in front
of the formula.
•5. Check to make sure each atom is
balanced
Additional Rules
•6. Check to make sure that all
coefficients are in the lowest
possible ratio
•**If no coefficient is written, the
coefficient is assumed to be “1”
• https://www.youtube.com/watch?v=zmdxMlb88Fs
Examples
• Balance the following
•H2 (g) + O2 (g)  H2O (l)
•Na (s) + Br2 (g)  NaBr (aq)
•AgNO3 (aq) + Cu(s)  Cu(NO3)2 (aq) + Ag(s)
Practice
Balance the following Equations
• FeCl3 + NaOH  Fe(OH)3 + NaCl
• CuCl2 + NaI  CuI2 + NaCl
• H2O2  H2O + O2
Balancing Equations
•AgI + Fe2(CO3)3  FeI3 + Ag2CO3
•Al4C3 + H2O  CH4 + Al(OH)3
Balance the following equations
KMnO4 + Be3N2  K3N + Be(MnO4)2
Fe + O2  Fe2O3
Al2O3 + H2  Al + H2O
SnO2 + H2  Sn + H2O
Balance the following Equations
•1) C6H6 + O2  CO2 + H2O
•2) Ni(OH)2 + HCl  NiCl2 + H2O
•3) Al(NO3)3 + H2SO4 Al2(SO4)3 + HNO3
•4) Pb(NO3)2 + CuSO4 PbSO4 + Cu(NO3)2
Practice Balancing Equations
•CH4 + O2  H2O + CO2
•Fe + Br2  FeBr3
•Sn(NO2)4 + K3PO4  KNO2 + Sn3 (PO4)4
•C2H6 + O2  CO2 + H2O
•C3H8O3 + O2  CO2 + H2O
Warm-Up
•Balance the following equations:
•
SnO2 + H2  Sn + H2O
•
Mg(OH)2 +
•
C6H12O6 +
HCl 
O2 
MgCl2 +
CO2 +
H2O
H2O
Chemical Reactions
•Chemical reaction, substances join together to
form new substances
•The original substances present are called
REACTANTS
•The new substances formed are called
PRODUCTS
Additional Symbols
in Chemical Reactions
•+ used to separate reactants or products
•(s) means chemical is in solid state
•(l) means chemical is in liquid state
•(g) means chemical is in gas state
•(aq) means aqueous which means the
chemical is dissolved in water
Other Symbols
• means something is added to
the reaction
•Usually this is heat
• Pt
means a catalyst (Pt) is
added
Skeleton Equations
•Skeleton (Formula) Equation- the rough form
of an equation
•It only shows the framework for the chemical
reaction
•Example: Fe + Cl2  FeCl3
•Question Why is Chlorine written as Cl2?
Diatomic Molecules
• Diatomic Molecules occur in nature
• They are shown as single atoms because
the molecules formed are more stable than
the individual atoms
• Diatomic Molecules are Hydrogen,
Nitrogen, Oxygen, Fluorine, Chlorine,
Bromine, and Iodine
• They are written as H2, N2, O2, F2, Cl2, Br2, I2
Write Skeleton Equations/Balance
Equations
• Solid Sodium metal reacts with Oxygen gas to
form solid Sodium Oxide
• Solid sulfur reacts with Fluorine gas to form
gaseous Sulfur Hexafluoride when heated
• Nitrogen reacts with Hydrogen to form Ammonia
(NH3) gas. Heat is required.
Write Skeleton Equations
• Solid Magnesium metal reacts with Chlorine
gas to form solid Magnesium Chloride.
•Aqueous Silver Nitrate reacts with aqueous
Sodium Chloride to form solid Silver Chloride
and aqueous sodium nitrate
Write the Skeleton Formula for the following
Liquid Potassium Permanganate reacts
with gaseous Hydrogen Chloride to
produce aqueous potassium chloride and
aqueous Manganese (II) Chloride and liquid
water and chlorine gas.
•**Remember that the diatomic elements
(Mr. BrINClHOF) appear with a subscript of
two when alone
Practice
•
Boron sulfide reacts violently with water to form
dissolved boric acid (H3BO3) and hydrogen sulfide
gas.
• When liquid phosphorus trichloride is added to
water, it reacts to form aqueous phosphorous
acid (H3PO3) and aqueous hydrochloric acid (HCl).