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Crystals. I. Crystals. Rigid bodies in which the particles are arranged in units that form a repeating pattern. This particle arrangement gives the crystal a definite shape. . A. True Solids. All true solid substances are crystalline They have a definite melting point

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I crystals l.jpg
I. Crystals

  • Rigid bodies in which the particles are arranged in units that form a repeating pattern.

  • This particle arrangement gives the crystal a definite shape.


A true solids l.jpg
A. True Solids

  • All true solid substances are crystalline

  • They have a definite melting point

  • They have flat faces with definite angles

  • Crystalline solids "cleave" along unit cell lines

http://www.minerals.net/mineral/carbonat/calcite/images/12cleave.jpg


B amorphous solids l.jpg
B. Amorphous Solids

  • Non-crystalline solids

  • Amorphous substances do not have a pattern when they break.

Shattered Glass

Amorphous Carbon

http://phycomp.technion.ac.il/~anastasy/seminar2/amorphous.jpg

http://www.sxc.hu/pic/m/n/ni/nickobec/76746_texture_shattered_glass_three.jpg


Which is crystalline which is amorphous l.jpg
Which is crystalline? Which is amorphous?

Amorphous

Crystalline


C steno s law l.jpg
C. Steno’s Law

  • All crystals of a substance have the same angle between their faces

  • An INTRINSIC (or intensive) property—does not depend on amount, size, etc.


Nicolaus steno 1699 l.jpg
Nicolaus Steno—1699

  • Discovered Steno’s duct; a duct of the salivary gland

  • Steno's law of superposition: layers of rock are arranged with the oldest on the bottom and the youngest on the top

  • Was ordained as a Roman Catholic priest in 1675


D forces holding crystals together l.jpg
D. Forces Holding Crystals Together

  • Hydrogen Bonds ex: Ice

  • Van der Waals Forces ex: Sugar

  • Ionic Bonds ex: NaCl, CaCl2

  • Metallic Bonds ex: Fe, Cu, Al


E unit cells l.jpg
E. Unit Cells

  • The simplest repeating unit in a crystal

  • The arrangement of these units is determined by the bond angle between the particles.

  • Crystals are made up of repeating unit cells

  • Ex: small & large diamonds have the same shape

Salt-NaCl

Salt magnified 40 times

http://www.scienceclarified.com/images/uesc_03_img0169.jpg

http://www.chem.cornell.edu/sl137/Pictures.dir/salt.jpg


Sample unit cells l.jpg
Sample Unit Cells

Simple Cubic

Body Centered Cubic

Face Centered Cubic


F space lattice l.jpg
F. Space Lattice

  • Three-dimensional arrangement of unit cells repeated over and over giving a crystal its overall geometric shape


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Vocabulary

a. Solute – the substance dissolved in a given solution

b. Solvent – a substance that dissolves another to form a solution.

  • Water is a solvent for sugar

    c. Saturated solution - a solution obtained when a solvent (liquid) can dissolve no more of a solute (usually a solid) at a particular temperature


Slide13 l.jpg

d. Unsaturated solution - a solution in which more solute can be dissolved

e. Supersaturated solution - a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances



F seed crystal l.jpg

Super can be dissolved

Saturated

Solution

Sugar crystals

f. Seed Crystal

Seed crystal = the initial crystal

  • With rock candy, need a small sugar crystal to get large candies

  • With fudge, seed crystals lead to large crystal growth and bad, grainy fudge.

http://www.sweetconnections.com/images/rock-candy.jpg



Ii vocabulary continued l.jpg
II. Vocabulary (continued) can be dissolved

h. Hydrated Crystals - Water molecules become chemically bonded to ions in the crystal.

  • Anhydrous Crystals Crystal without water

CuSO4• 5 H2Oa hydrated crystal


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Slide19 l.jpg

j. Desiccant - Anhydrous substances that gain water so easily that they can be used to remove water from other substances.

ex: Silica gel packets found in new shoes…


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k. Hygroscopic - a solid whose ions capture water molecules out of the air

l. Deliquescent - a solid so strongly hygroscopic that it slowly dissolves in air

http://images.google.com/imgres?imgurl=http://boomeria.org/chemlectures/crystals/deliquescent.jpg&imgrefurl=http://boomeria.org/chemlectures/crystals/crystals.html&h=401&w=504&sz=115&hl=en&sig2=iV1JdCtiIovAn31pgV0Opw&start=5&tbnid=2k87VM9a7qPD4M:&tbnh=103&tbnw=130&ei=lZT5Rf2qCJquiQH1p8TBBQ&prev=/images%3Fq%3Ddeliquescent%26svnum%3D10%26hl%3Den%26safe%3Dactive


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m. Viscosity - the property of a fluid that resists the force tending to cause the fluid to flow. (how “sticky” a liquid is)


How does temperature affect viscosity l.jpg
How does Temperature Affect Viscosity? force tending to cause the fluid to flow. (how “sticky” a liquid is)


Iii dissociation review l.jpg
III. Dissociation Review force tending to cause the fluid to flow. (how “sticky” a liquid is)

Na+ (aq) + Cl-(aq)

NaCl(s) 

___ moles of solute

CaBr2 (s) 

___ moles of solute

Mg3(PO4)2 (s) 

___ moles of solute

C6H12O6 (s) 

___ moles of solute

2

Ca+2 (aq) + 2 Br-1 (aq)

IONIC

3

3 Mg+2 (aq) + 2PO4-3 (aq)

5

C6H12O6 (aq)

COVALENT

1


Iv freezing pt depression boiling pt elevation l.jpg
IV. Freezing Pt Depression & Boiling Pt Elevation force tending to cause the fluid to flow. (how “sticky” a liquid is)

FACT:

1 mole of solute per liter of water lowers the freezing point by

And

Increases the boiling point by

1.86o C

0.51o C


B why do solutes reduce the freezing point l.jpg
b. Why do solutes reduce the freezing point? force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • solute interferes with formation of space lattice.


C why do solutes increase the boiling point l.jpg

P force tending to cause the fluid to flow. (how “sticky” a liquid is)atm

t = 1 min

c. Why do solutes increase the boiling point?

  • solute lowers the vapor pressure, harder to boil.

Pvap


Examples l.jpg
Examples: force tending to cause the fluid to flow. (how “sticky” a liquid is)

20.00 g of MgCl2 is dissolved in 100 ml of water. What is the change in boiling & freezing points?

MgCl2 Mg+2+ 2 Cl-1

# solute particles?

3

0.21 mol MgCl2 x 3 mol solute =

0.63 mol of solute particles in 100 ml water


Real life examples l.jpg
Real Life Examples force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • Why do we use salt on roads?

    • To decrease the freezing point

  • Which is better, NaCl or CaCl2?

    • CaCl2 3 particles of solute

  • Is sugar a good de-icer?

    • NO! Only 1 particle of solute


Why use antifreeze in your car l.jpg
Why use antifreeze in your car? force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • To keep water in radiator from freezing

  • Freezing water will crack radiatorIce expands as it freezes

  • To keep water in radiator from boiling


Slide30 l.jpg

  • Homemade ice cream force tending to cause the fluid to flow. (how “sticky” a liquid is)

    • You add salt to the ice to decrease its temperature allowing the cream to freeze more easily, quickly with fewer large crystals  grainy ice cream


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FP/BP Quiz force tending to cause the fluid to flow. (how “sticky” a liquid is)

5.0 g Na2SO4 is dissolved in 100 ml of water.

1) Calculate the grams of Na2SO4 in 1000 ml H2O

2) Calculate the moles of Na2SO4 in 1000 ml H2O

3) Write the dissociation equation and determine the moles of solute in 1000 ml H2O

Na2SO4 2Na+ + SO42-

0.35 mol  1.05 mol solute

4) Calculate DTFP (Freezing Point Depression)

5) Calculate the new Boiling Point


Antifreeze sample problem l.jpg
Antifreeze Sample Problem force tending to cause the fluid to flow. (how “sticky” a liquid is)

A sample of antifreeze contains 100 mol of ethylene glycol (covalent) in 5 L of water. Calc the FP & BP.

  • FP

  • BP

New freezing point?

-37.2 oC (-35oF)

New boiling point?

110.2 oC (230oF)


Ice cream sample problem l.jpg
Ice Cream Sample Problem force tending to cause the fluid to flow. (how “sticky” a liquid is)

What mass of rock salt is needed in 1 L of water to lower the freezing point to -10oC?

Freezing Point depression?

How many moles of solute are needed?

Dissociation Eqn? How many moles of NaCl? grams?

NaCl  Na+ + Cl-

10oC

1:2

5.4 moles solute

2.7 moles


V hydrated crystals l.jpg
V. Hydrated Crystals force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • Ex:

    CuSO4 • 5H2O + heat CuSO4 + 5 H2O

    (Blue) (White)

Hydrate

Anhydrous

Hydrate


Slide35 l.jpg

  • Hydrates – crystals with water force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • Anhydrous – crystal with no water

  • Water of Hydration:

    1) The amount of water in a crystal

    2) Water of hydration is a definite ratio

    FeSO4  3 H2O

    MW = __________

55.8 + 32.1 + 4(16.0) + 3 (18) = 189.9 g/mol


Naming l.jpg
Naming: force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • 1 H2O monohydrate

  • 2 H2O dihydrate

  • 3 H2O trihydrate

  • 4 H2O tetrahydrate

  • 5 H2O pentahydrate

  • 6 H2O hexahydrate

  • 7 H2O heptahydrate

  • 8 H2O octahydrate

  • 9 H2O nonahydrate

  • 10 H2O decahydrate


Problem solving l.jpg
Problem Solving force tending to cause the fluid to flow. (how “sticky” a liquid is)

1) Find the % H2O in Sodium Sulfide trihydrate.

Na2S • 3H2O


Problem solving38 l.jpg
Problem Solving force tending to cause the fluid to flow. (how “sticky” a liquid is)

2) If 10 grams of Na2S  3 H2O is heated ______ grams of water will be lost. (40.9% water)

3) 1 mole of Na2S combines with ___ moles of H2O?

0.409 x 10.0 = 4.09 g of water lost

3

Na2S • 3H2O

The ratio is 1 to 3


Problem solving39 l.jpg
Problem Solving force tending to cause the fluid to flow. (how “sticky” a liquid is)

4) If 0.03 moles of CuSO4 is combined with 0.15 moles water, what is the formula? name?

5) If 0.04 mol of BeCl2 is combined with 0.08 mol water, what is the formula?

The ratio is 1 to 5

CuSO4• 5H2O

Copper (II) sulfate pentahydrate

The ratio is 1 to 2

BeCl2• 2H2O

Beryllium chloride dihydrate


Problem solving40 l.jpg
Problem Solving force tending to cause the fluid to flow. (how “sticky” a liquid is)

3.94 g CuCl2

i. mass of anhydrous crystal?

ii. moles of anhydrous crystal?

iii. moles of water?

iv. experimental mole ratio

v. formula of hydrated crystal?

vi. name of hydrated crystal?

6) Five grams of hydrated CuCl2 crystals lose 1.06 g of water when heated.

1 to 2 ratio

CuCl2• 2H2O

Copper (II) chloride dihydrate


Vii allotropes l.jpg
VII. Allotropes force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • Any of several crystalline forms of a chemical element. Ex. Charcoal, graphite, and diamond are all allotropes of carbon


Sulfur l.jpg
Sulfur force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • S8 2 crystalline forms: rhombic & monoclinic

  • Sx 1 amorphous form: brown, plastic sulfur

    • Formed by rapid cooling

    • Will crystallize over time


Phosphorous l.jpg

White phosphorous shells force tending to cause the fluid to flow. (how “sticky” a liquid is)

Phosphorous

White Phosphorous Video (skip to the middle) http://video.google.com/videoplay?docid=1124770688802666702


Carbon l.jpg
Carbon force tending to cause the fluid to flow. (how “sticky” a liquid is)

  • Graphite – 2 dimensional bonding

    • VdW's forces between layers

    • brittle, breaks in layers

  • Diamond – 3 dimensional bonding

    • Hard and Durable

  • Fullerenes – C60 C70


  • Eight common allotropes of carbon l.jpg
    Eight common allotropes of carbon force tending to cause the fluid to flow. (how “sticky” a liquid is)

    Diamond

    Graphite

    Bucky ball

    Nanotube

    http://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Eight_Allotropes_of_Carbon.png/333px-Eight_Allotropes_of_Carbon.png


    Slide46 l.jpg


    Oxygen l.jpg
    Oxygen Diamond?

    • O2 “normal” oxygen in the air we breathe.

    • O “nascent oxygen” –very reactive

    • O3 ozone— A thin layer in the upper atmosphere’ reflects UV light back into space.


    Ozone the good the bad the ugly l.jpg
    Ozone: The Good, The Bad, & the Ugly Diamond?

    • Good: protects us from harmful UV rays

    • By banning CFC’s that destroy atmospheric ozone we’ve decreased the holes in the ozone layer.


    Ozone action days l.jpg
    “Ozone action days” Diamond?

    • Weather conditions are favorable for ground-level ozone (smog) to reach unhealthy levels within our region, and your voluntary actions are requested. Please help and make a difference on this OZONE ACTION DAY by doing any of the following:

    • Car pool or use mass transit when possible

    • Bike to work

    • Refuel automobiles later in the evening

    • Postpone lawn mowing until the evening

    • Postpone using paints, lacquers and solvents until late in the afternoon

    • Reduce or postpone, when possible, industrial processing activities which produce VOC emissions

    • Reduce your demand for electricity


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