ions in aqueous solutions and colligative properties chapter 13 modern chemistry

Chapter 13 Section 1 Comp. in Aq. Soln p. 434-445

1

Ions in Aqueous Solutions and Colligative Properties

Chapter 13 Modern Chemistry

Sections 1 & 2Compounds in Aqueous SolutionsColligative Properties of a Solution


2

Compounds in Aqueous Solutions

Section 13.1


3

VOCABULARYDissociation Equation PrecipitateNet Ionic EquationSpectator IonIonizationHydronium IonStrong ElectrolyteWeak Electrolyte


4

Conce

pt

Map

13

.1

NET IONIC EQUATIONS

DISSOCIATION

EQUATION

PRECIPITATE

REACTIONS

SPECTATOR

IONS

IONIZATION

HYDRONIUM ION

STRONG ELECTROLYTE

WEAK ELECTROLYTE

DISSOCIATION


5

Dissociation Equations• Dissociation is the separation of ions that

occurs when an ionic compound dissolves• Dissociation equations show how an ionic

solid breaks into ions when it dissociates.

• Don’t forget to balance the equation or add state of matter symbols.

NaCl (s) Na1+(aq)

+ Cl1-(aq)

CaCl2 (s) Ca2+(aq)

+ 2Cl1-

(aq)


6

Dissociation Equations

• CaCl2 gives three ions per formula unit – one calcium and two chlorine.

• When one mole of CaCl2 dissociates…

• One mole of calcium ions are produced• Two moles of chloride ions are produced• Three moles of ions – total- are produced

CaCl2 (s) Ca2+(aq)

+ 2Cl1-

(aq)


7

1. Write the equation for the dissolution of aluminum sulfate, Al2(SO4)3 , in water. How many moles of aluminum ions and sulfate ions are produced by dissolving 1 mol of aluminum sulfate? What is the total number of moles of ions produced by dissolving 1 mol of aluminum sulfate?

p. 4

36

Al2(SO4)3 (s) 2Al3+ (aq) + 3SO4 2−(aq)

2 mol aluminum ions, 3 mol sulfate ions

5 ions total

Dissociation Sample Problem


8

1. Write the equation for the dissolution of each of the following in water, and then determine the number of moles of each ion produced as well as the total number of moles of ions produced.

a. 1 mol ammonium chloride

b. 1 mol sodium sulfide

c. 0.5 mol barium nitrate

p. 4

36

Dissociation Practice Problems


9

a. NH4Cl (s) NH4 1+ (aq) + Cl 1−

(aq)

1 mol ammonium ions; 1 mol chloride ions; 2 mol total ions

b. Na2S (s) 2Na1+ (aq) + S 2−(aq)

2 mol sodium ions; 1 mol sulfide ions; 3 mol total ions

c. Ba(NO3)2 (s) Ba2+ (aq) + 2NO3 1−(aq)

1 mol barium ions; 2 mol nitrate ions; 3 mol total ions

p. 4

36

Dissociation Practice Problems


10p. 437

Solubility of Ionic Compounds


11p. 437

General Solubility Guidelines


12



13



14p. 438(NH

4) 2

S +

Cd(N

O3) 2


15

NET IONIC EQUATION• Write the balanced equation for the

reaction between ammonium sulfide and cadmium II nitrate. Be sure to include states of matter

• What type of reaction is it? What are the products?(NH4)2S (aq) + Cd(NO3)2 (aq)

2 NH4NO3 (aq) + CdS

(s)


16

NET IONIC EQUATION

Each (aq) is dissociated. The (s) is not dissociated; it is the precipitate.Write the dissociation equation for each (aq).(NH4)2S (s) 2 (NH4)1+

(aq) + S2-(aq)

Cd(NO3)2 (s) Cd2+(aq) + 2 NO3

1- (aq)

2 NH4NO3 (aq) 2 NH41+

(aq) + 2 NO31- (aq)

(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)


17

NET IONIC EQUATION(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)

(NH4

)S

+ +

Cd

1+ 2-

(aq) (aq)

(NO3

)

2+ 1-

(aq) (aq)

NH4NO3

+ +1+ 1-

(aq) (aq)

2 2 2 2

CdS

+(s)

Break all (aq) into ions; not the (s)

Balance and add states


18


(s)

(NH4

)S+ + Cd

1+ 2-

(aq) (aq)

(NO3

)

2+ 1-

(aq) (aq)

NH4NO3+ +

1+ 1-

(aq) (aq)

2 2 2 2 CdS+(s)

Identify spectator ions and remove

Write what’s left.

+


19

2-


(s)

(NH4

)

S

+ +

Cd

1+

(aq)

(aq)

(NO3

)

2+

1-

(aq)

(aq)

NH4NO3+ +

1+ 1-

(aq) (aq)

2 2 2 2

CdS

+

(s)

This is the net ionic equation.

+


20

Ag(NO3) + NaCl


21

NET IONIC EQUATION• Write the balanced equation for the

reaction between sodium chloride and silver nitrate. Be sure to include states of matter

• What type of reaction is it? What are the products?NaCl (aq)+ Ag(NO3) (aq) NaNO3 (aq)+ AgCl (s)


22

NET IONIC EQUATION

Each (aq) is dissociated. The (s) is not dissociated; it is the precipitate.Write the dissociation equation for each (aq).NaCl (s) Na1+

(aq) + Cl1-(aq)

Ag(NO3) (s) Ag1+(aq) + NO3

1- (aq)

NaNO3 (aq) Na1+ (aq) + NO3

1- (aq)

NaCl (aq) + AgNO3 (aq) NaNO3 (aq) + AgCl (s)


23


NET IONIC EQUATIONN

aCl

+ +

Ag

1+ 1-

(aq) (aq)

NO3

1+ 1-

(aq) (aq)

NaNO3

+ +1+ 1-

(aq) (aq)

AgCl

+(s)

Break all (aq) into ions; not the (s)

Balance and add states


24

+


NET IONIC EQUATION

Na

Cl+ + Ag1+ 1-

(aq) (aq)

NO31+ 1-

(aq) (aq)

Na

NO3+1+ 1-

(aq) (aq)

AgCl+(s)

Identify spectator ions and remove

Write what’s left.

+


25


+


NET IONIC EQUATION

Na

Cl

+ +

Ag

1+

1-

(aq)

(aq)

NO3

1+

1-

(aq)

(aq)

Na

NO3+1+ 1-

(aq) (aq)

AgCl

+

(s)

+


26

2-


(s)

(NH4

)

S

+ +

Cd

1+

(aq)

(aq)

(NO3

)2+

1-

(aq)

(aq)

NH4NO3+ +

1+ 1-

(aq) (aq)

2 2 2 2

CdS

+

(s)


+


27

Identify the precipitate that forms when aqueous solutions of zinc nitrate and ammonium sulfide are combined. Write the equation for the possible double-displacement reaction. Then write the formula equation, overall ionic equation, and net ionic equation for the reaction.

p. 4

40

Zn 2(aq) S 2−(aq) →ZnS (s)

Sample Problem p. 440


28

1. Will a precipitate form if solutions of potassium sulfate and barium nitrate are combined? If so, write the net ionic equation for the reaction.

2. Will a precipitate form if solutions of potassium nitrate and magnesium sulfate are combined? If so, write the net ionic equation for the reaction.

p. 4

40

2. No

Practice Problems p. 440

1. Yes; Ba 2(aq) SO4 2−(aq) →BaSO4 (s)


29

3. Will a precipitate form if solutions of barium chloride and sodium sulfate are combined? If so, identify the spectator ions and write the net ionic equation.

4. Write the net ionic equation for the precipitation of nickel(II) sulfide.

p. 4

40

4. Ni 2(aq) S 2−(aq) →NiS (s)

Practice Problems p. 440

3. Yes; Naand Cl−; Ba 2(aq) SO4 2−(aq) →BaSO4 (s)


30

Ionization vs. Dissociation

• Covalent compounds

• Ions are formed from solute molecules when they dissolve.

• Ionic compounds• Ions are already

present – the ions are separated by the water molecules.


31Dis

soci

ati

on &

Ioniz

ati

on


32

Ionization• Usually occurs with polar molecules• If the strength of a bond within the solute

molecule is weaker than the attractive forces of the solvent molecules, then the covalent bond of the solute breaks and the molecule is separated into ions.

• The ions are hydrated – just like ions from dissociation.

HCl (g) H1+(aq)

+ Cl1-(aq)


33

Hydronium ion, H3O+

• H+ ion does not exist by itself.• H+ ion bonds to a water molecule to form

H3O+, a hydronium ion.

• Better described as a reaction.

H2O (l) + HCl (g)

H3O+(aq) + Cl-(aq)


34

• A solution which contains all (or most) of the solute in the form of ions.

• The solute is completely dissociated.

Strong Electrolytes

CaCl2 (s) 1 mole

Ca2+(aq)

+ 2Cl1-

(aq)

1 mole 2 moles+2 -1-1


35

• A solution which contains some of the solute in the form of ions, but most of the molecules stay intact.

• The solute is slightly ionized.

Weak Electrolytes

HF (aq) + H2O (l) 1 mole

H3O+(aq)

+ F1-(aq)

0.05 mol 0.05mol


36p. 442*

Electrolytes

ions in aqueous solutions and colligative properties chapter 13 modern chemistry

Documents

mol chloride ions

mol sulfide ions

mol nitrate ions

mol sodium ions

1aq1 mol ammonium ions

separation of ions

moles of aluminum ions

mol of aluminum sulfate