Chemistry 40S Unit 1 – reactions in aqueous solutions - PowerPoint Presentation

Presentation on theme: "Chemistry 40S Unit 1 – reactions in aqueous solutions"— Presentation transcript

Slide1

Chemistry 40S

Unit 1 – reactions in aqueous solutions

Lesson 2

Learning 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

Solubility 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

Writing 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

Writing net ionic equations

Step

2: Balance the

equation

BaCl

2

+

Na

2

SO

4



BaSO

4

+

2

NaCl

Writing 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

Writing 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

Writing 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

Solubility rules

A set of rules to help you predict if and what precipitate will form when combining ionic solutions.