UNIT 4: CHEMICAL REACTIONS DAY
3 NOTES
- TYPES OF REACTIONS REVIEW
- SOLUBILITY
- NET IONIC EQUATIONS
Ms. Kondra & Mr. Olnhoff
TYPES OF REACTIONS:
Synthesis/Combination/Formation
Decomposition
Single replacement
Double displacement
Combustion
A. SYNTHESIS/COMBINATION/FORMATION
When 2 or more _______________ combine to produce a more
___________ substance
e.g. magnesium burns in air forming magnesium oxide
e.g. to make ammonia fertilizer (NH3), nitrogen from the
air reacts with
hydrogen gas
Demo: burning magnesium
B. DECOMPOSITION
the __________ of synthesis
when a more _________ substance breaks down into 2
or more
_________ parts
e.g. When heated, potassium chlorate decomposes
into potassium chloride
and oxygen gas
e.g. When carbonic acid (hydrogen carbonate)
decomposes it forms pure
water and carbon dioxide bubbles appear. {By the
way, this reaction can be
reversed to make carbonic acid.}
Demo: potassium chlorate & gummy bear+
C. SINGLE REPLACEMENT/DISPLACEMENT
-When a ________ element replaces the _______ in an
ionic compound
or
When a ____________ element replaces the _________ in
an ionic compound
Use activity series on p. 136 & 216 to see if reaction
will actually occur or not
e.g. If iron is added to a solution of copper sulfate,
solid copper will form at
the bottom of the container.
e.g. When chlorine gas is added to seawater (a
solution of sodium bromide),
bromine gas is produced.
Demo: The confused blue solution
D. DOUBLE REPLACEMENT/DISPLACEMENT
- Always involves _________ compounds
- The ________ of one compound changes places
with the cation of the second
- Often a __________, ______, or _______ will be one of
the products* (*we will write 'net ionic equations'
for these later)
- Use solubility table on p. 459 to check if product
is a precipitate
e.g. When mixed, lead (II) nitrate and sodium
iodide solutions form a bright yellow precipitate.
What is the name of this precipitate?
e.g. When ammonium sulfide and iron (II) sulfate
solutions are mixed a precipitate of iron sulfide
forms. What is the other product?
BALANCE THE FOLLOWING:
(CHECK YOUR ACTIVITY SERIES CHARTS TO
SEE IF THE RXN CAN HAPPEN)
1.
___Cl2 + ___NaI  ___NaCl + ___I2
2.
___Ca + ___HOH  ___Ca(OH)2 + ___H2
3.
___Pb + ___HCl  ___PbCl2 + ___H2
4.
___Zn + ___CuCl2  ___ZnCl2 + ___Cu
5.
___Br2 + ___CaCl2  ___CuBr2 + ___Cl2
BALANCE THE FOLLOWING AND USE YOUR
SOLUBILITY CHART TO DETERMINE THE
STATE OF EACH COMPOUND
1.
___CaCl2
+ ___Na2 SO4 
2.
___AgNO3 + ___NaI 
3.
___MgSO4 + ___NaOH 
EXAMPLE 1
Devise a procedure for separating a mixture of
Ba2+ and Pb2+ by precipitating them individually.
EXAMPLE 2
A solution contains a mixture of Cl- and OH-.
Devise a procedure for precipitating each of these
separately.
E. COMBUSTION
- Involves burning a substance in __________
- If a hydrocarbon is burnt, the products are
always __________, __________ & ___________
e.g. In a barbeque, propane gas is burnt as
the fuel. Write the equation.
e.g. Write the equation for the combustion of
butane in a lighter.
Demo: whoosh bottle
ASSIGNMENT:
Textbook: Page 464 #2-7
NET IONIC EQUATIONS
So far, the chemical equations we have looked at
have been MOLECULAR EQUATIONS.
A more detailed chemical equation that shows all
the particles and ions of a solution as they
realistically exist is called a COMPLETE IONIC
EQUATION.
The molecular equation below does not show
some details of this reaction.
AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)
NET IONIC EQUATIONS
AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)
•When a salt solution is added to another salt
solution, a precipitate (an insoluble compound)
may form.
•For example, when aqueous silver nitrate, AgNO3,
is added to aqueous sodium chloride, NaCl, a
white solid forms and settles out of solution.
•To focus on the formation of the precipitate AgCl,
it is useful to write the equation to show the ions
separately.
NET IONIC EQUATIONS
AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)
This is how they exist in solution:
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ® AgCl(s) + Na+(aq) + NO3-(aq)
(Ag
NO3(aq) +
Na
Cl(aq) ® AgCl(s) +
Na
NO3(aq))
•Cancel
out the things that don’t change from one side of the
reaction to the other.
•Now
we can see that only the Ag+ ion and the Cl- ion are involved
in the reaction.
•The
sodium and nitrate ions are called SPECTATOR IONS because
they are unchanged in the reaction.
NET IONIC EQUATIONS
AgNO3(aq) + NaCl(aq) ® AgCl(s) + NaNO3(aq)
This is how they exist in solution:
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ® AgCl(s) + Na+(aq) + NO3-(aq)
Cancel out the spectator ions, and what is left is called the NET
IONIC EQUATION.
Net Ionic Equation: Ag+(aq) + Cl-(aq) ® AgCl(s)
NET IONIC EQUATIONS
Net ionic equations can be written for any ion exchange
reaction in solution.
To write net ionic equations, follow these rules:
1.
Write a balanced equation showing the reactant(s) and
product(s) before separation.
2.
Repeat the equation with reactant(s) and product(s)
separating ionic compounds where appropriate.
3.
Cancel all spectator ions and rewrite the remaining net
ionic equation.
NET IONIC EQUATIONS
- Used for describing double replacement
reactions
- A simplified equation that shows the species
directly involved in forming the precipitate, gas,
or water
e.g. Write the net ionic equation for the reaction
between lead nitrate and potassium iodide
1st - write the balanced formula equation:
2nd - write the TOTAL IONIC EQUATION:
3rd - cancel out the SPECTATOR IONS & write
the net ionic equation
Demo with lead nitrate and potassium iodide
ASSIGNMENT:
Net Ionic Worksheet Handout