CHEM 120: Introduction to Inorganic Chemistry

Instructor: Upali Siriwardane (Ph.D., Ohio State University)

CTH 311, Tele: 257-4941, e-mail: upali@chem.latech.edu

Office hours: 10:00 to 12:00 Tu & Th ; 8:00-9:00 and 11:00-12:00 M,W,& F

Chapters Covered and Test dates

Tests will be given in regular class periods from 9:30-10:45 a.m. on the following days:

September 22,     2004 (Test 1): Chapters 1 & 2

October 8,           2004(Test 2): Chapters 3, & 4

October 20,         2004 (Test 3): Chapter 5 & 6

November 3,        2004 (Test 4): Chapter 7 & 8

November 15,      2004 (Test 5): Chapter 9 & 10

November 17,      2004 MAKE-UP: Comprehensive test (Covers all chapters

Grading:

[( Test 1 + Test 2 + Test3 + Test4 + Test5)] x.70 + [ Homework + quiz average] x 0.30 = Final Average

                                            5

Chapter 7: Reactions and Solutions

1. Types of chemical reactions : combination, decomposition, or replacement.

2. Classes of chemical reactions: precipitation, reactions with oxygen, acid–base, and oxidation–reduction.

3. Solution terms: solution, solute, and solvent.

4. Kinds of solutions: gas/liquid, liquid/ liquid, solid/liquid

5. Solubility and equilibrium.

6. Solution concentration: weight/volume percent and weight/weight percent.

7. Solution concentration: molarity.

8. Dilution: Preparing solutions.

9. Interconvert molar concentration of ions and illiequivalents/liter.

10. Concentration-dependent solution properties: Collegative properties.

11. Unique chemical and physical properties of water.

12. Role of electrolytes in blood and their relationship to the process of dialysis.

Writing chemical reactions

We can classify some chemical reactions according to certain patterns that are observed. This helps us to predict the products of reactions.

Combination reactions

Combination Reaction

Decomposition reactions

Replacement reactions: single replacement

Replacement reactions: double replacement

Classify as to type of reaction

2Al(OH)₃(s) g Al₂O₃(s) + 3H₂O(g)

Fe₂S₃(s) g 2Fe(s) + 3S(s)

Na₂CO₃(aq) + BaCl₂(aq) g BaCO₃(s) + NaCl(aq)

C(s) + O₂(g) g CO₂(g)

Types of chemical reactions

Precipitation reactions: mix reactants together and get an insoluble precipitate (not soluble in water).

How do you know what cmpds are insoluble?

Learn table 7.1

"1A salts,"

1A salts, NO₃^-’s, acetates (CH₃COO^-), NH₄⁺’s are very soluble.

Cl^-’s, Br^-’s and I^-’s are soluble except when combined with Ag⁺, Pb²⁺, Hg₂²⁺.

CO₃^2-’s, PO₄^3-’s, S ^2-’s generally insoluble (except for 1A’s and NH₄⁺)

OH^-’s: Ba²⁺, 1A’s are soluble; others generally insoluble

**The SO₄^2-’s of Ba²⁺, Ag⁺, Ca²⁺, Sr²⁺, Pb²⁺are insoluble. Others are soluble.

Are these soluble?

Ag₂SO₄

Li₂S

Pb(NO₃)₂

AgCl

BaSO₄

(NH₄)₂SO₄

Predict whether get precipitation when mix

Zinc sulfate and barium chloride

Sodium sulfate and potassium chloride)

Ammonium carbonate and calcium chloride

Strontium nitrate and potassium phosphate

Reactions with oxygen

Combustion Reactions: When compounds containing C and H react with O₂(burning or combustion) get CO₂ and H₂O. (Greenhouse effect)

Corrosion: 4Fe(s) + 3O₂(g) g 2Fe₂O₃(s) rust

Acid-base reactions

Acid-base reactions involve transfer of a H⁺ from the acid (starts with H) to the base (hydroxide) to form a salt and water

Oxidation-reduction will be covered in Chapter 9

Properties of solutions

A solution is a homogeneous mixture of two or more substances and is made up of a solvent and one or more solutes.

The solutes are the species that are being dissolved in the solvent. The solvent is usually present in the greater amt.

An aqueous solution has ________ as the the solvent.

Types of solutions

gas in gas --air

gas in liquid--soda

gas in solid--gas on solid catalyst

liquid in liquid

liquid in solid--mercury amalgam

solid in liquid

solid in solid--14-karat gold

"Ionic compounds (electrolytes)"

Ionic compounds (electrolytes) dissociate into ions when dissolved in water. The solutions conduct electricity.

Molecular compounds in general do not dissociate into ions in aqueous solution. The solutions do not conduct electricity and are ________________.

Properties of solutions

1. A solution is a ___________ mixture. Each species in the solution

2. retains its ________ identity.

3. __________composition

4.clear and transparent (but can have color)

5. remains uniform throughout for all time

6. can be separated into its components by ___________ means.

"Solute size is _________________."

Solute size is _________________.

The solute cannot be separated from the solvent by paper filtration.

Colloids (colloidal suspension)

Colloids: have similar properties as solutions but the particle size is

Colloids behave differently when exposed to light.

________ effect helps distinguish between solutions and colloids.

Homogenized milk is a _____________.

"Emulsions,"

Emulsions, suspensions; larger particle size than solutions. Solute separates on standing.

Particle size is > 200nm.

Filterable.

Degree of solubility

Can dissolve different amounts of solute in solvent.

Maximum amount of solute that can be dissolved in a given amt of solvent at a given temp:____________

"Say a solution is __________..."

Say a solution is __________ if the maximum amount of solute is dissolved in a given solvent.

Solid Dsolution

Dynamic equilibrium set up between dissolved and undissolved solute

Maximum amout of solute that can be dissolved in a given amt of solvent at a given temp: solubility

"If a solution has less..."

If a solution has less than the max amt dissolved:

If a solution has more than the max amount dissolved: ______________: unstable--excess solute will fall to bottom and form a precipitate.

Factors that affect solubility

Like dissolves like--smaller difference in polarity between solute and solvent, more soluble.

Polar solutes in polar solvents

Non-polar solutes in non-polar solvents

Ionic solids in polar solvents

Factors that affect solubility

I. Temperature

A. ionic compound in water:

B. Gas in water:

Factors that affect solubility

II. Pressure

A. Pressure changes have little effect on the solubility of a solid or liquid in another liquid.

Pressure effects continued

B. The solubility of a gas in a liquid

"Under 1 atm total pressure"

Under 1 atm total pressure, the partial pressure of O₂ is 159 mmHg and the solubility of O₂ in blood is 44g/100mL.

In Denver (mile high city) P_O2= 132mmHg and the solubility of O₂ in the blood is 37g/100mL

Mt Whitney (2.5miles high) P_O2 = 98 mmHg and the solubility of O₂ in the blood is 27g/100mL

Mt Everest (5.8 miles) P_O2 = 52 mmHg and the solubility of O₂ in the blood is 14g/100mL

Problem

The solubility of N₂ in blood at 37^oC and at a partial pressure of 0.80 atm is 5.6 x 10^-4 mol/L.

A deep sea diver breathes compressed air with the partial pressure of N₂ equal to 4.0 atm. How much N₂ is dissolved in the blood at this pressure?

Concentration of solutions:

Concentration gives us the amount of solute dissolved in a given amt of solvent or in a given amt of solution.

There are different ways of expressing concentration.

Percent (W/V %)

Weight/volume percent

weight/volume% (W/V%)=

(mass of solute in g¸ vol of soln in mL) x 100%

Note that the volume of a solution does not equal the volume of solute and solvent.

Percent (W/W%)

Weight/weight percent

Weight/weight % (W/W%) = (mass of solute ¸ mass of solution) x 100%

The mass of the solution =

Problems

Calc the composition of the soln in W/V%: 20.0g acetic acid in 2.50L sollution

Calc the W/W % of 31.0 g of KCl in 152 g of water.

Calc the W/W% of 50.0 g KCl in 5.00 x 10² mL solution (d = 1.14g/mL)

"How many grams of solute..."

How many grams of solute are needed to prepare:

A. 2.50 x 10² g of 5.00% (W/W) NH₄Cl

B. 2.50 x 10² mL of 3.50% (W/V) Na₂CO₃

Calc the amount of water that must be added to 5.00 g of urea (NH₂)₂CO in the preparation of a 16.2 W/W % by mass solution.

Molarity M

Molarity (M) = moles of solute ¸ vol of soln in L

units of molarity: mol of solute/L solution

M = moles solute(M )/V and #moles = M x V

Molarity and W/V% are temperature dependent.

Molarity problems

Calc the molarity of 20.0g acetic acid in 2.50L solution.

Calc the no of grams of solute needed to make 2.50 x 10² mL of 0.200M KOH.

Calc the volume, in ml, needed to provide 2.14g of NaCl from a 0.270M solution.

Dilution

When a solution is diluted you add more solvent. The no. of moles of solute does not change. (#moles= M x V)

So initial vol x molarity (mol/L) = # mol solute and final vol x new molarity = same # moles # mol_i = # mol_f

So M_iV_i = M_fV_f

Dilution problems

50.0mL of a 0.250M sucrose soln was diluted to 5.00 x 10² mL. What is the molar conc of the resulting solution?

A 6.00 mL portion of an 8.00M stock solution is to be diluted to 0.400M. What will be the final volume after dilution?

Molality (m)

molality (m) = moles of solute/mass in kg of solvent

A 2.5m (molal) NaCl solution has 2.5moles of NaCl dissolved in 1000g or 1kg of solvent

Molality is temperature independent.

Concentration-dependent solution properties

Colligative properties are properties

"So NaCl(aq)"

So NaCl(aq) g Na ⁺(aq) + Cl^-(aq)

K₂SO₄(aq) g 2K⁺(aq) + SO₄^2-(aq)

C₁₂H₂₂O₁₁(aq) g C₁₂H₂₂O₁₁(aq)

"We are going to examine..."

We are going to examine the effect of adding a solute to a solvent on

1. vapor pressure

2. freezing point

3. boiling point

4. osmosis

Remember that colligative properties depend only on the number of particles in solution and not on their identity.

Vapor pressure

When a solute is added to a solvent the vapor pressure (equilibrium) of the solution is lower than that of the pure solvent. (explain)

Raoult observed the relationship between the amount of the solvent and the vapor pressure of the solution

Effects on freezing and boiling points

What effect does vp lowering have on the freezing pt and boiling pt of a solution?

Since the vapor pressure of the solution is lower than the vapor pressure of the pure solvent,

"When a nonvolatile solute is..."

When a nonvolatile solute is added to a solvent the freezing point of the solution is lowered. (explain)

Math relationship for b.pt. elevation and f. pt depression

Dt_f = I mk_f k_f is the freezing pt constant

i = no of particles in solution per formula unit

For molecular species i =1

For NaCl i =                 These i values

For K₂SO₄ i =                assume 100%

For Al₂(SO₄)₃ i =           ionization.

For water k_f = 1.86^oC/m

"Dt_b= imk_b"

Dt_b= imk_b k_b is the b. pt. constant; m is the molality of the solution and i is the no. of particles in solution.

For water k_b =0.52^oC/m

"What are the normal freezing..."

What are the normal freezing and boiling pts of

a. 58.5g NaCl in 100. g of water

b. 60.0 of urea [(NH₂)₂CO] in 100. g of water.

Osmosis

Certain materials allow passage of molecules of a certain size through but not bigger molecules. These are called __________________ membranes.

When have pure solvent and a solution separated by a semipermeable membrane (or 2 solutions of different concentrations), “nature” wants the concentrations in the 2 sides to be the same.

"So the solvent moves from..."

So the solvent moves from the less concentrated to the more concentrated side to try to make the concs of the 2 solns the same. Process is called

Osmotic pressure (p) is the

Slide 53

"p="

p= I MRT where M is the molarity of the soln; R = 0.0821 L atm/Kmol and T is the temp in Kelvin

Have to remember that osmosis is a colligative property and depends on the no of particles in solution and not their identity.

Slide 55

"Blood:"

Blood: 0.30M on particles

0.90% saline and 5.0% glucose are also 0.30 M --isotonic with blood (intracellular fluids)

Osmosis problems

Calc the osmotic pressure of 0.50M NaCl and 0.50M sucrose. Assume a temp of 25^oC.

Compare 0.50M NaCl and 0.50M Sucrose

Which has higher m. pt?

Which has higher b. pt?

Which has higher vapor pressure?

Each solution is separated from water by a semipermeable membrane. Which solution has the higher osmotic pressure?


	Instructor: Upali Siriwardane (Ph.D., Ohio State University)
	CTH 311, Tele: 257-4941, e-mail: upali@chem.latech.edu
	Office hours: 10:00 to 12:00 Tu & Th ; 8:00-9:00 and 11:00-12:00 M,W,& F


	Tests will be given in regular class periods from 9:30-10:45 a.m. on the following days:
	September 22, 2004 (Test 1): Chapters 1 & 2
	October 8, 2004(Test 2): Chapters 3, & 4
	October 20, 2004 (Test 3): Chapter 5 & 6
	November 3, 2004 (Test 4): Chapter 7 & 8
	November 15, 2004 (Test 5): Chapter 9 & 10
	November 17, 2004 MAKE-UP: Comprehensive test (Covers all chapters
	Grading:
	[( Test 1 + Test 2 + Test3 + Test4 + Test5)] x.70 + [ Homework + quiz average] x 0.30 = Final Average
	5


	1. Types of chemical reactions : combination, decomposition, or replacement.
	2. Classes of chemical reactions: precipitation, reactions with oxygen, acid–base, and oxidation–reduction.
	3. Solution terms: solution, solute, and solvent.
	4. Kinds of solutions: gas/liquid, liquid/ liquid, solid/liquid
	5. Solubility and equilibrium.
	6. Solution concentration: weight/volume percent and weight/weight percent.
	7. Solution concentration: molarity.
	8. Dilution: Preparing solutions.
	9. Interconvert molar concentration of ions and illiequivalents/liter.
	10. Concentration-dependent solution properties: Collegative properties.
	11. Unique chemical and physical properties of water.
	12. Role of electrolytes in blood and their relationship to the process of dialysis.


	We can classify some chemical reactions according to certain patterns that are observed. This helps us to predict the products of reactions.


	2Al(OH)₃(s) g Al₂O₃(s) + 3H₂O(g)

	Fe₂S₃(s) g 2Fe(s) + 3S(s)

	Na₂CO₃(aq) + BaCl₂(aq) g BaCO₃(s) + NaCl(aq)

	C(s) + O₂(g) g CO₂(g)


	Precipitation reactions: mix reactants together and get an insoluble precipitate (not soluble in water).
	How do you know what cmpds are insoluble?
	Learn table 7.1


	1A salts, NO₃^-’s, acetates (CH₃COO^-), NH₄⁺’s are very soluble.
	Cl^-’s, Br^-’s and I^-’s are soluble except when combined with Ag⁺, Pb²⁺, Hg₂²⁺.
	CO₃^2-’s, PO₄^3-’s, S ^2-’s generally insoluble (except for 1A’s and NH₄⁺)
	OH^-’s: Ba²⁺, 1A’s are soluble; others generally insoluble
	**The SO₄^2-’s of Ba²⁺, Ag⁺, Ca²⁺, Sr²⁺, Pb²⁺are insoluble. Others are soluble.


	Zinc sulfate and barium chloride
	Sodium sulfate and potassium chloride)
	Ammonium carbonate and calcium chloride
	Strontium nitrate and potassium phosphate


	Combustion Reactions: When compounds containing C and H react with O₂(burning or combustion) get CO₂ and H₂O. (Greenhouse effect)


	Corrosion: 4Fe(s) + 3O₂(g) g 2Fe₂O₃(s) rust


	Acid-base reactions involve transfer of a H⁺ from the acid (starts with H) to the base (hydroxide) to form a salt and water


	Oxidation-reduction will be covered in Chapter 9


	A solution is a homogeneous mixture of two or more substances and is made up of a solvent and one or more solutes.
	The solutes are the species that are being dissolved in the solvent. The solvent is usually present in the greater amt.
	An aqueous solution has ________ as the the solvent.


	gas in gas --air
	gas in liquid--soda
	gas in solid--gas on solid catalyst
	liquid in liquid
	liquid in solid--mercury amalgam
	solid in liquid
	solid in solid--14-karat gold


	Ionic compounds (electrolytes) dissociate into ions when dissolved in water. The solutions conduct electricity.

	Molecular compounds in general do not dissociate into ions in aqueous solution. The solutions do not conduct electricity and are ________________.


	1. A solution is a ___________ mixture. Each species in the solution
	2. retains its ________ identity.
	3. __________composition
	4.clear and transparent (but can have color)
	5. remains uniform throughout for all time
	6. can be separated into its components by ___________ means.


	Solute size is _________________.

	The solute cannot be separated from the solvent by paper filtration.


	Colloids: have similar properties as solutions but the particle size is

	Colloids behave differently when exposed to light.
	________ effect helps distinguish between solutions and colloids.
	Homogenized milk is a _____________.


	Emulsions, suspensions; larger particle size than solutions. Solute separates on standing.
	Particle size is > 200nm.
	Filterable.


	Can dissolve different amounts of solute in solvent.

	Maximum amount of solute that can be dissolved in a given amt of solvent at a given temp:____________


	Say a solution is __________ if the maximum amount of solute is dissolved in a given solvent.
	Solid Dsolution
	Dynamic equilibrium set up between dissolved and undissolved solute
	Maximum amout of solute that can be dissolved in a given amt of solvent at a given temp: solubility


	If a solution has less than the max amt dissolved:

	If a solution has more than the max amount dissolved: ______________: unstable--excess solute will fall to bottom and form a precipitate.


	Like dissolves like--smaller difference in polarity between solute and solvent, more soluble.
	Polar solutes in polar solvents
	Non-polar solutes in non-polar solvents
	Ionic solids in polar solvents


	II. Pressure
	A. Pressure changes have little effect on the solubility of a solid or liquid in another liquid.


	Under 1 atm total pressure, the partial pressure of O₂ is 159 mmHg and the solubility of O₂ in blood is 44g/100mL.

	In Denver (mile high city) P_O2= 132mmHg and the solubility of O₂ in the blood is 37g/100mL

	Mt Whitney (2.5miles high) P_O2 = 98 mmHg and the solubility of O₂ in the blood is 27g/100mL

	Mt Everest (5.8 miles) P_O2 = 52 mmHg and the solubility of O₂ in the blood is 14g/100mL


	The solubility of N₂ in blood at 37^oC and at a partial pressure of 0.80 atm is 5.6 x 10^-4 mol/L.
	A deep sea diver breathes compressed air with the partial pressure of N₂ equal to 4.0 atm. How much N₂ is dissolved in the blood at this pressure?


	Concentration gives us the amount of solute dissolved in a given amt of solvent or in a given amt of solution.

	There are different ways of expressing concentration.


	Weight/volume percent
	weight/volume% (W/V%)=
	(mass of solute in g¸ vol of soln in mL) x 100%

	Note that the volume of a solution does not equal the volume of solute and solvent.


	Weight/weight percent
	Weight/weight % (W/W%) = (mass of solute ¸ mass of solution) x 100%
	The mass of the solution =


	Calc the composition of the soln in W/V%: 20.0g acetic acid in 2.50L sollution

	Calc the W/W % of 31.0 g of KCl in 152 g of water.

	Calc the W/W% of 50.0 g KCl in 5.00 x 10² mL solution (d = 1.14g/mL)


	How many grams of solute are needed to prepare:
	A. 2.50 x 10² g of 5.00% (W/W) NH₄Cl
	B. 2.50 x 10² mL of 3.50% (W/V) Na₂CO₃

	Calc the amount of water that must be added to 5.00 g of urea (NH₂)₂CO in the preparation of a 16.2 W/W % by mass solution.


	Molarity (M) = moles of solute ¸ vol of soln in L
	units of molarity: mol of solute/L solution
	M = moles solute(M )/V and #moles = M x V

	Molarity and W/V% are temperature dependent.