Lesson 2 Learning outcomes C12102 Perform a laboratory activity to develop a set of solubility rules C12103 Use a table of solubility rules to predict the formation of a precipitate Solubility rules ID: 792264
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Slide1
Chemistry 40S
Unit 1 – reactions in aqueous solutions
Lesson 2
Slide2Learning outcomes
C12-1-02:
Perform a laboratory activity to develop a set of solubility rules
C12-1-03:
Use a table of solubility rules to predict the formation of a precipitate
Slide3Solubility rules
Solubility rules allow people to predict if a precipitate will form, and if one does---what it is!
Solubility rules rely on standard known
solubilities
for ions at STP (standard temperature and pressure:
0
C and 101.3
kPa
)
In order to use the solubility rules to your advantage when
predicting the product of the combination of two ionic solutions
you must be able to write a
net ionic equation
Slide4Writing net ionic equations
Step 1: Predict the products of the reaction and ensure that the equation is balanced
Think double-displacement reaction
Example: Reaction between BaCl2 and Na2SO4
BaCl
2
+ Na
2
SO
4
BaSO
4
+
NaCl
Slide5Writing net ionic equations
Step
2: Balance the
equation
BaCl
2
+
Na
2
SO
4
BaSO
4
+
2
NaCl
Slide6Writing net ionic equations
Step 3: Use a table of solubility rules to identify which ionic substances will precipitate from aqueous solutions
Precipitate is a solid
give it an ‘s’ subscript and the rest an ‘
aq
’ subscript
BaCl
2(
aq
)
+ Na
2
SO
4(
aq
)
BaSO
4(s)
+ 2NaCl
(
aq
)
This is known as a
balanced molecular equation
Slide7Writing net ionic equations
Step
4: Separate the aqueous solutions into
their ions
Ba
2
+
(
aq
)
+
2Cl
-
(
aq
)
+ 2Na
+
(
aq
)
+ SO4
2-
(
aq
)
BaSO
4(s)
+ 2Na
+
(
aq
)
+ 2Cl
-
(
aq
)
This is known as an
ionic
equation
Slide8Writing net ionic equations
Step 5: Cancel out spectator ions
Ba
2+
(
aq
)
+
2Cl
-
(
aq
)
+
2Na
+
(
aq
)
+ SO4
2-
(
aq
)
BaSO
4(s)
+
2Na
+
(
aq
)
+
2Cl
-
(
aq
)
Ba
2+
(
aq
)
+ SO4
2-
(
aq
)
BaSO
4(s)
This is a net ionic equation
Slide9Solubility rules
A set of rules to help you predict if and what precipitate will form when combining ionic solutions.