Handout 3 – Chem 1A - Saddleback College€¦ · 3.6 Determining the Formulas of Compounds ... (molar mass of ethylene glycol = 62.07 g/mole) ... C. Freezing Point Depression –

Chem 1A Fall 2013 Dr. White 1

Handout 3– Chem 1A Notes for Experiment 10 3.6 Determining the Formulas of Compounds

A. Formulas B. Determining empirical formula from data:

Lecture Example: Find the empirical formula for the oxide that contains 42.05 g of nitrogen and 95.95 g of oxygen. Lecture Example: Ascorbic acid (vitamin C) contains only C, H, and O. Combustion of ascorbic acid produced 40.9% C and 4.5% H. What is the empirical formula for Ascorbic Acid?

Lecture Example: What is the molecular formula if the molar mass of Ascorbic Acid was formed to be 176 g/mole?


10.1 Intermolecular Forces of Attraction (IMFs) A. IMFs –

Intermolecular forces vs. Intramolecular Forces

B. States of Matter and IMFs

Particle Proximity Shape and Volume Particle Energy

of Motion (Ek) Strength of IMFs compared to Ek

1. Gas

2. Liquid

3. Solid


10.2 The Liquid State (Basic Properties) A. Surface tension

B. Capillarity C. Viscosity

10.3-10.7 Structures and Types of Solids A. The 2 Broad Categories of Solids


B. Structure of Matter

C. Types of Crystalline Solids 1. Ionic Solids

Properties of Ionic Solids:

Attractive Forces Melting Points and Boiling Points

Water Solubility Electrical Conductivity*

*electrical conductivity -


2. Metallic Solids

Properties of Ionic Solids:


Water Solubility Electrical Conductivity

3. Macromolecular (Network) Solids


Properties of Network Solids: Attractive Forces Melting Points and

Boiling Points Water Solubility Electrical

Conductivity

4. Noble Gas Solids

Properties of Noble Gas Solids:



5. Nonpolar Molecular Solids


Properties of Nonpolar Molecular Solids: Attractive Forces Melting Points and

Boiling Points Water Solubility Electrical

Conductivity

6. Polar Molecular Solids

Properties of Polar Molecular Solids:




IMF Examples: 1. What are the forces of attraction between molecules of the following substances? • PCl3

• I2

• HF 2. Rank the following molecules from strongest to weakest intermolecular forces of attraction that exist in a pure sample. Cl2, H2O, and H2S

D. Melting Points of Solids 1. Ionic Solids


Lecture Example: In each of the following, predict which of the following has the larger magnitude lattice energy and which has the higher melting point.

a. KF and KCl b. KCl and MgCl2

2 and 3. Metallic and Macromolecular


4, 5, and 6. Noble gases, nonpolar molecular and polar molecular


E. Bonding in Solids: MO Theory


F. Band Gap Size and Conductivity

1. Conductors

Chem 1A Dr. Abel 16

D. Band Gap Size –

1. Conductors – 2. Insulators – 3. Semiconductors –

E

Chem 1A Dr. Abel 15

C. Bonding in Solids: MO Theory

Unfilled MOs

Filled MOs


2. Insulators 3. Semiconductors


Notes for Lab Activity 11 10.4 Structure and Bonding in Metals

A. Unit Cell 1. 2-D Unit Cell

B. 3-Dimensional Packing in Solids

1. Square Packing

2. More efficient packing:


C. Cubic Unit Cell Types 1. Body Centered Cubic (BCC)

a. based on square packing

http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/sphere8.swf

Box 8 in the lab: Atoms per unit cell

From the lab:

Body diagonal length in terms of r:


Side length in terms of r (Box 6) Volume in terms of r (Box 7) Using 4/3(πr3) as the volume of a spherical atom, calculate the percentage of the

body-centered cubic unit cell that is occupied by atoms. This can be done by dividing the volume of the equivalent number of atoms found in the unit cell, by the volume of the unit cell, and multiplying by 100%. (Box 9)

Sodium crystals are body-centered cubic, and the sodium atoms have a radius of 0.186 nm. Calculate the density of sodium. (Box 10)

Chromium crystals are body-centered cubic, and have a density of 7.20 g/mL. Calculate the radii of chromium atoms. (Box 11)

2. Simple Cubic (SC) [you will explore this in your lab activity, so you should fill in this info on your own]

a. based on square packing


3. Face Centered Cubic (FCC) [you will explore this in your lab activity, so you should fill in this info on your own] a. based on cubic closest packing



4. Summary: (fill in after the lab activity) Atoms/unit cell Edge length (in

terms of r) Packing Efficiency

(percentage of unit cell occupied by atoms)*

SC

BCC

FCC

D. Ionic Solids also adopt unit cells 1. NaCl

2. Zinc Sulfide


10.8 Changes of State (phase changes) A. Phase Changes


B. Heating Diagrams

Lecture Example: Calculate the heat needed to covert 12.0 g of ice at -5.0°C to gas at 104.0°C. Given Information: Sice = 2.092 J/g°C Swater = 4.184 J/g°C Ssteam = 2.008 J/g°C ΔH°fusion = 6.01 kJ/mol ΔH°vap = 44.0 kJ/mol (continue calculation on next page)


10.9 Phase Diagrams

A. Intro to Phase Diagrams

B. Example Phase Diagrams

A

B

C D

Pres

sure

Temperature


4.1 Water, the common solvent A. The Polar Nature of Water

A

B

C D Pr

essu

re

Temperature


B. Ionic Compounds in Water

C. Covalent (Molecular Compounds) In Water

4.2 The nature of aqueous solutions – strong and weak electrolytes

A. Types of Electrolytes


4.3 The Composition of Solutions A. Liquid Solutions B. Concentration –

Lecture Examples: a. An aqueous solution of NaNO3 is prepared in the lab by using 0.38 g of NaNO3 and a 50-mL volumetric flask. What is the molarity of the solution?

b. An experiment calls for 0.184 g of aqueous sodium hydroxide. How many mL of 0.150 M NaOH needs to be added to get 0.184 g of sodium hydroxide?


c. What is the molarity of sodium ion in a solution made by mixing 3.58 mL of 0.348 M sodium chloride with 50.0 mL of 0.681M sodium sulfate (assume the volumes are additive).

C. Dilutions –

Lecture Example: Your instructions tell you to use 25.0 ml of 3.0 M NaOH, but only 5.0 M solution remains on the shelf. How many ml of the 5.0 M solution should you dilute to 25.0 ml to obtain a 3.0 M solution?


Chapter 11 – Properties of Solutions 11.1 Solution Composition A. Units of Concentration

1. Molarity (M) 2. Molality (m)

Lecture Example: How many grams of MgCl2 are required to make 0.250 m MgCl2 using 75.0 g of water?

3. Mass Percent –

Lecture Example: What is the mass percent of sucrose in a solution that contains 22.3 g sucrose in 105.0 g of water?

4. Mole Fraction –


Lecture Example: What is the mole fraction of glucose in a solution containing 5.67 g of glucose (molar mass is 180.16), C6H12O6, dissolved in 25.27 g water?

5. Normality (N) –

Lecture example: What is the Normality of a 1.00 M H2SO4 solution?

B. Converting Between Concentration units 1. Leture Example: A sample of aqueous HCl is 11.8 M HCl and has a density of 1.190 g/mL.

Solute = _______________ Solvent = ______________ Mass (g) # Moles Volume (mL)

Solute Solvent

Solution (total)


(a) What is the mass percent of HCl in solution? (b) What is the molality of HCl in solution? (c) What is the normality of the HCl solution?

2. If the density at 20°C of 4.028 m solution of ethylene glycol in water is 1.024 g/mL, what is the molarity of the solution? (molar mass of ethylene glycol = 62.07 g/mole)


Solute Solvent

Solution (total)


3. The density of acetonitrile, CH3CN, is 0.786 g/mL, and the density of methanol, CH3OH, is 0.791 g/mL. A solution is made by dissolving 20.0 mL CH3OH in 100.0 mL CH3CN. The volumes are additive for this solution.


Solute Solvent

Solution (total)

(a) What is the mole fraction of methanol in the solution?

(b) What is the molality of the solution?

(c) Assuming that the volumes are additive, what is the molarity of CH3OH in solution?

11.3 Factors Affecting Solubility in Liquids

A. “Like Dissolves Like”


B. Lecture Examples: Which pairs are miscible and which are immiscible? 1. H2O and NH3

2. Br2 (l) and H2O (l) 3. C9H19OH (l) and C6H14 (l)

11.4 Vapor Pressures of Solutions

A. Non-volatile solutes


Lecture Example: Calculate the vapor pressure of a solution prepared by dissolving 175 g of glucose into 350.0 mL water at 75°C. The vapor pressure of pure water at 75°C is 289.1 mm Hg and its density is 0.97489 g/mL.

B. Volatile Solutes Lecture Example: What is the vapor pressure at 25°C of a solution that contains 0.724 mole fraction of a substance with a vapor pressure of 154 mmHg in water? The vapor pressure of water at this temperature is 23.8 mmHg.


Lecture Example: A solution contains equal moles of benzene (C6H6) and toluene (C7H8). At 25°C, the vapor pressure of pure benzene is 95.1 torr and that of pure toluene is 28 torr. What is the vapor pressure of each component and what is the total vapor pressure? 11.5 Boiling Point Elevation and Freezing Point Depression

A. Colligative Properties

B. Boiling Point Elevation Lecture Example: If a solution is obtained by dissolving 1.921 g of magnesium chloride in 48.92 g of water, what is the boiling point of the solution? The Kb for water is 0.512°C/m.


Lecture Example: How much NaCl needs to be added to 1.00 kg of water to increase the boiling point by 1.0°C? The Kb for water is 0.512°C/m.

C. Freezing Point Depression – Lecture Example: What is the minimum molality of an ethylene glycol (C2H6O2 – antifreeze) solution (in water) that will protect the solution from freezing at -18°C? Kf for water is 1.86°C/m.


Lecture Example: Camphor (a molecular substance) freezes at 179.5 °C and has a Kf = 40. °C/m. A solution was made by adding 1.07 g of an unknown molecular compound to 78.1 g of camphor. The solution froze at 176.0 °C. What is the molar mass of the unknown substance?

D. Phase Diagram Showing Freezing Point Depression and Boiling Point Elevation:

11.6 Osmotic Pressure (Π)


Lecture Example: What is the osmotic pressure that develops when a 0.020M aqueous glucose solution is separated from water by a semi-permeable membrane? An aqueous solution was made by dissolving 3.50 mg of protein in sufficient water to make 5.00 mL of solution. The osmotic pressure of the solution at 25°C was 1.54 torr. What it the molar mass of the protein? 11.7 Colligative Properties of Electrolytic Solutions

A. van’t Hoff Factor is not always as predicted

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Handout 3 – Chem 1A - Saddleback College€¦ · 3.6 Determining the Formulas of Compounds ... (molar mass of ethylene glycol = 62.07 g/mole) ... C. Freezing Point Depression –