Warm-up: 11/15
*formula review*
Write formulas for the following:
1. trisulfur tetroxide
2. sulfuric acid
3. lead (IV) phosphate
Dihydrogen monoxide
• Is present in cases of excessive sweating and vomiting
• A major component of acid rain
• Can cause severe burns in the gaseous state
• Accidental inhalation can kill you
• Primary contributor to erosion
• Decreases effectiveness of automobile brakes
• Is associated with major cyclonic events
• May dissolve metal ions especially in the presence of road salt
• Reacts violently with certain metals, such as sodium and potassium
**HAVE YOU EVER COME IN CONTACT WITH THIS CHEMICAL
COMPOUND??
**WRITE THE FORMULA FOR THE COMPOUND.
**Are there ANY benefits to this compound?
Chemical Reactions
What is a chemical reaction?
• A chemical reaction
is the process by
which the atoms of
one or more
substances are
rearranged to form
different
substances.
Chemical Reaction Indicators
• Some ways to tell that a chemical
reaction have occurred include:
1. Color change – a fast change indicates the
particles have changed.
2. Heat content change – did the temperature go up or
down.
3. Gas is produced – if it bubbles (without being
heated) it’s a gas!
4. Precipitate forms – a precipitate is a solid produced
during a chemical reaction between solutions.
Chemical Equations
• Chemical equations are used to
represent chemical reactions.
Fe (s) + Cl2 (g)
Reactants

FeCl3 (s)
Products
Symbols Used in Equations
+
(s)
Used to separate two reactants
or products
“Yields” separates reactants
from products
Identifies solid state
(l)
Identifies liquid state
(g)
Identifies gaseous state
(aq)
Identifies aqueous state – a
substance dissolved in water

Ticket Out
Choose the correct equation for the following:
1. B. Calcium reacts with water to yield calcium
hydroxide and hydrogen.
C. a. Ca2 + H2O → CaOH + H
B. b. Ca + HO2 → CaOH2 + H2
E.
c. Ca + H2O → Ca(OH)2 + H2
2. Iron reacts with Bromine to produce
Iron(II)bromide.
a. Fe2 + Br → Fe2Br
b. Fe + Br2 → FeBr2
c. Fe2 + Br2 → Fe2Br2
Warm-Up
• Which of the following is a chemical change?
A. Water is decomposed into hydrogen gas and oxygen gas.
B. Water droplets collect on the outside of a glass filled with ice.
C. A boiling pot of water produces steam.
D. Water is frozen into ice.
• As Cyndie mixed two liquids together, she observed the
resulting mixture was hotter than either of the two liquids
before they were mixed. What had caused this increase in
temperature?
A. Electricity had been generated.
B. A physical change had occurred.
C. A chemical reaction had occurred.
D. Hydrogen bonds in the water had been broken.
Balanced equations
• Chemical equations MUST be balanced to
show that the number of atoms in the
reactants is the same as the number in
the products.
What goes in MUST come out!!!
*Law of Conservation of Mass/Matter*
Rules for Balancing
• The only place you can change any
number is the coefficient.
• A coefficient is a number written in
front of a chemical formula.
• Don’t forget diatomic molecules.
• Use the smallest ratio of coefficients
possible.
How to Balance
• If you are starting with words, write
the equation using formulas.
Example: hydrogen and oxygen gases
react to form water. (Hint: diatomics!)
H2 +
O2

H2O
Things To Do:
• Draw boxes around each formula: you can
NEVER change anything in the boxes
(including subscripts)!!!
• Inventory your individual atoms for both
reactant side and product side
• Write numbers in front of the boxes
(coefficients) until inventory of reactants
matches inventory of products
Problems and How to try to fix
them:
• Try lowest common denominators
• If you think you want to use a
fraction/decimal—DON’T!! Instead try
sticking a 2 in front of the largest molecule
in the equation and start again.
• Keep you Inventories CURRENT!
Practice Problems
• _NaCl + _BeF2 → _NaF + _BeCl2
• _ AgNO3 + _ LiOH → _AgOH + _LiNO3
• _FeCl3 + _Be3(PO4)2
_BeCl2 + _FePO4
H2 +
O2

H2O
2 hydrogens + 2 oxygens  2 hydrogens 1 oxygen
Notice that there are two hydrogen
atoms on each side however there are
two oxygen atoms in the reactants but
only one in the products. To balance this
we must insert a coefficient.
H2 +
O2

2 H2O
While that evens the number of oxygen
atoms – there are now four hydrogen
atoms in the products. To balance the
hydrogen we go back to the reactants
and insert a coefficient.
2H2 +
O2

2H2O
Now there are equal number of atoms of
hydrogen and oxygen on each side of
the equation – it is now balanced.
Ticket Out
• Which balanced formula is correct:
1. SnO2 + H2 → Sn + H2O
a. 2SnO2 + 3H2 → 2Sn + 3 H2O
b. Sn3O2 + 3H2 → Sn + 2 H2O
c. SnO2 + 2H2 → Sn + 2 H2O
2. Al + HCl → AlCl3 + H2
a. Al + 6HCl → AlCl3 + 3H2
b. 2Al + 3HCl → 2AlCl3 + 3H2
c. Al + 6HCl → AlCl3 + 3H2
Warm-up:
• Write the formulas for the equation and
then balance it.
• Solid aluminum reacts with solid iodine to
produce solid aluminum iodide.
Types of Reactions
• There are five types of chemical
reactions: synthesis, decomposition,
single-replacement, double-replacement,
and combustion.
• Replacement reactions are sometimes
called displacement reactions.
• Synthesis reactions are also called
combination reactions.
Synthesis or Combination
• Synthesis is a reaction in which two or
more substances react to produce a
single product.
A +
B  AB
Na +
Cl2 
2NaCl
Decomposition Reactions
• Decomposition reactions occur when a single
compound breaks down into two or more
simpler substances.
AB  A + B
or
ABC  A + BC
2HI  H2 + I2
2Mg(ClO3)2 2MgCl2 + 3O2
Single-Replacement Reactions
• A reaction in which the atoms of one
element replace the atoms of another
element in a compound.
A + BC 
AC + B
Mg + Zn(NO3)2  Mg(NO3)2 + Zn
Double-Replacement Reactions
• A reaction involving the exchange of
positive ions between two ionic
compounds dissolved in water.
AB + CD  AD + CB
2NaOH + CuCl2  2NaCl + Cu(OH)2
Combustion Reactions
• In a combustion reaction, oxygen
combines with a substance and releases
energy in the form of heat and light.
CH4 + 2O2  CO2 + 2H2O
*All hydrocarbons contain carbon and
hydrogen and burn in oxygen to yield
the same products – CO2 and H2O
Heat Content Changes
• An exothermic reaction occurs when more
energy is released forming new bonds than is
required to break bonds in the initial
reactants. *These reactions tend to feel
warm.
• An endothermic reaction occurs when a
greater amount of energy is required to break
the existing bonds in the reactants than is
released when the new bonds form in the
products. *These reactions tend to feel cold.