Transcript Unit 2 Matter and Energy

Honors
Chemistry
Unit 2:
Matter and Energy
Guiding Questions
Why do substances boil or freeze at different
temperatures?
Why do we put salt on the roads in the winter?
Why does sweating cool us?
What is energy?
How do we measure energy?
Matter
Introductory Definitions
(…pull out your vocab!)
matter: anything having mass and volume
mass: the amount of matter in an object
weight: the pull of gravity on an object
volume: the space an object occupies
units: L, dm3, mL, cm3
state of matter: solid, liquid, or gas
L3
Solid, Liquid, Gas
(a) Particles in solid
(b) Particles in liquid
(c) Particles in gas
composition: what the matter is made of
copper:
many Cu atoms
water:
many groups of
2 H’s and 1 O
properties: describes matter
what it looks like, smells like, etc.
how it behaves
Qualitative observations
atom: a basic building block of matter
~100 diff. kinds
1
The Periodic Table of
Elements
H
6
7
8
9
10
13
14
15
16
17
18
30
31
32
33
34
35
36
47
48
49
50
51
52
53
54
78
79
80
81
82
83
84
85
86
110
111
112
113
114
115
116
117
118
4
11
12
19
20
21
22
23
24
25
26
27
28
29
37
38
39
41
41
42
43
44
45
46
55
56
57
72
73
74
75
76
77
87
88
89
104
105
106
107
108
109
Rb Sr
Cs Ba
Fr Ra
58
59
B C N O F
Al Si P
Na Mg
K Ca
He
5
3
Li Be
2
Zr Nb Mo Tc Ru Rh Pd Ag Cd
La Hf Ta W Re Os Ir
In Sn Sb Te I
Pt Au Hg
61
62
63
64
65
66
67
68
69
Uut Fl Uup Lv Uus Uuo
70
71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
90
91
92
93
94
95
96
97
98
99
100
101
Xe
Tl Pb Bi Po At Rn
Ac Rf Db Sg Bh Hs Mt Ds Rg Cp
60
S Cl Ar
Ga Ge As Se Br Kr
Sc Ti V Cr Mn Fe Co Ni Cu Zn
Y
Ne
102
Select an element
103
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
(
= Internet link )
Other Physical DATA
Elements  contain only one type of atom
1. monatomic elements consist of unbonded,
“like” atoms
e.g., Fe, Al, Cu, He
2. polyatomic elements consist
of several “like” atoms bonded
together
diatomic elements: H2 O2 Br2 F2 I2 N2 Cl2
“HOBrFINCl = Hoberfinckle”
others:
P4 or S8
“BrINClHOF = Brinklehoff”
Diatomic Elements, 1 and 7
H2
N2 O2 F2
Cl2
Br2
I2
allotropes: different forms of the same element in
the same state of matter
OXYGEN
CARBON
oxygen gas(O2)
elemental
carbon
graphite
diamond
buckyball
ozone (O3)
Allotropes
of Carbon
Graphite
Diamonds
Allotropes of
Carbon
C60 & C70
“Buckyballs”
“Buckytubes”
Buckminsterfullerene
Buckminster Fuller was known for designing
geodesic domes, like Epcot Center
Allotropes of
Carbon
Carbon nanotubes
Allotropes of
Carbon
Graphene
Chem Matters Graphene Video
Super strong and super conductive
molecule: a neutral group of bonded atoms
Description
Chemical
Symbol
1 oxygen atom
O
1 oxygen molecule
O2
2 unbonded
oxygen atoms
2O
1 phosphorus
atom
P
1 phosphorus
molecule
P4
4 unbonded
phosphorus
atoms
4P
Model
Elements may consist of either molecules or unbonded atoms
Compounds
…contain two or more different types of atoms
…have properties that are different from
those of their constituent elements
Na (sodium): explodes in water
table salt
(NaCl)
Cl2 (chlorine): poisonous gas
neutron
“bullet”
Atoms can be altered only
nuclear means
by _______
Molecules can be altered
chemical means
by ________
U
(i.e., chemical reactions)
Atomic blast at Hiroshima
e.g., DehydrationKr
of sugar Ba
C12H22O11(s)  12 C(s) + 11 H2O(g)
Electrolysis of water
2 H2O(l)  2 H2(g) + O2(g)
Classifying Matter
(Pure) Substances …have a fixed composition
…have fixed properties
ELEMENTS
COMPOUNDS
e.g., Fe, N2, S8, U
e.g., H2O, NaCl, HNO3
sulfur (S8)
sodium chloride (NaCl)
Pure substances have a chemical formula
Mixtures
two or more substances mixed together
…have varying composition
…have varying properties
The substances are NOT chemically bonded,
and they… retain their individual properties
Tea, orange
juice, oceans,
and air are all
mixtures
Two Types of Mixtures
1. homogeneous: (or solution)
particles are microscopic; sample has the same
composition and properties throughout;
evenly mixed
Oh Yeah!
e.g.,
salt water
Kool Aid
alloy: a homogeneous mixture of metals
e.g.,
bronze (Cu + Sn) pewter (Pb + Sn) brass (Cu + Zn)
Two Types of Mixtures (cont.)
2. heterogeneous:
different composition and properties in the
same sample; unevenly mixed
tossed salad
e.g.,
raisin bran
suspension: settles over time
e.g.,
paint
snowy-bulb gifts
Chart for Classifying Matter
MATTER
Has NO chemical formula
Has a chemical formula
PURE SUBSTANCE
Made of 1 element
MIXTURE
Made of 2 or more
different elements
Unevenly mixed
ELEMENT
COMPOUND
HETEROGENEOUS
HOMOGENEOUS
Uniform or evenly mixed throughout (a solution)
Double Bubble Mind Map
Alike
Different
Topic
Different
Topic
Mixture vs. Compound
Different
Alike
Variable
Composition
Involve
substances
Topic
No bonds
between
components
Can be
separated by
physical means
Mixture
Different
Fixed
Composition
Topic
Contain
two or more
elements
Can be
separated
into
elements
Compound
Bonds
between
components
Can ONLY be
separated by
chemical means
Contrast…
24K GOLD
24/24 atoms are gold
pure gold
element
Au
14K GOLD
14/24 atoms are gold
mixture of gold & other
metals
homogeneous mixture
e.g., Au + Cu
Compound Composition
All samples of a given compound
Always have the same composition
Every sample of NaCl tastes the
same, melts at the same temp.,
and is 39.3% Na and 60.7% Cl
by mass.
Phosgene gas (COCl2) is 12.1% carbon,
16.2% oxygen, and 71.7% chlorine by
mass. Find # of g of each element in
254 g of COCl2.
C: 254 g (0.121) = 30.7 g C
O: 254 g (0.162) = 41.1 g O
Cl: 254 g (0.717) = 182 g Cl
A sample of butane (C4H10) contains 288 g carbon
and 60. g hydrogen. Find…
A. …total mass of sample
288 g C + 60 g H = 348 g
B. …% of each element in butane
288 g C
= 0.828
%C=
348 g
60. g H
= 0.17
%H=
348 g
82.8% C
17 % H
C. …how many g of C and H are in a 24.2 g sample
C: 24.2 g (0.828) = 20.0 g C
H: 24.2 g (0.17) =
4.2 g H
24.2 g
A 550 g sample of chromium (III) oxide (Cr2O3)
has 376 g Cr. How many grams of Cr and O
are in a 212 g sample of Cr2O3?
376 g Cr
% Cr =
550 g
68.4% Cr
and
31.6% O
100 %
Cr: 212 g (0.684) = 145 g Cr
O: 212 g (0.316) =
67 g O
chromium (III) oxide
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Elemental Analysis of Human Body
(by mass %)
Oxygen (65%)
Carbon (18%)
Hydrogen (10%)
Nitrogen (3%)
Calcium (1.5%)
Phosphorus (1.0%)
Potassium (0.35%)
Sulfur (0.25%)
Sodium (0.15%)
Magnesium (0.05%)
Copper, Zinc, Selenium, Molybdenum, Fluorine,
Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%)
• Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium,
Arsenic, Bromine (trace amounts)
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Elemental Analysis of Human Body
(by # of atoms)
Hydrogen (63%)
Oxygen (24%)
Carbon (12%)
Nitrogen (0.58%)
Calcium (0.24%)
Phosphorus (0.14%)
Sulfur (0.038%)
Sodium (0.037%)
Potassium (0.033%)
Magnesium (0.0070%)
Iron (0.00067%)
A sample of bronze contains 68 g copper and 7 g tin
A. Find total mass of sample
68 g Cu + 7 g Sn = 75 g
B. Find % Cu and % Sn
68 g Cu
90.7% Cu and 9.3% Sn
% Cu =
75 g
C. How many grams of each element does
a 346 g sample of bronze contain?
(Bronze is a mixture and isn’t necessarily
always 90.7% Cu and 9.3% Sn.)
We don’t know!
However, assuming these % are correct…
Cu: 346 g (0.907) = 314 g Cu (and 32 g Sn)
Separating Mixtures
…involves physical means, or physical changes
1. sorting: by color,
shape,
texture,
etc.
2. filter: particle size
is different
Episode 5
filtration in the chemistry laboratory
filtration in the “real world”
Separating Mixtures (cont.)
3. magnet: one substance must
contain iron
4. chromatography: some substances dissolve
more easily than others
Separating Mixtures (cont.)
5. density: “sink vs. float”
perhaps use a centrifuge
blood after highspeed centrifuging
decant: to pour
off the liquid
Separating Mixtures (cont.)
6. distillation: different boiling points
thermometer
water out
(warmer)
water in
(cooler)
more-volatile
substance
(i.e., the one
with the lower
boiling point)
mixture
more-volatile
substance, now
condensed
heat source
No chemical reactions
are needed to separate mixtures;
substances are NOT bonded
dental amalgam
ONE OF THESE
Properties of Matter
CHEMICAL properties tell how a substance
reacts with other substances
PHYSICAL properties can be observed
without chemically changing the substance
EXTENSIVE properties depend on the amount
of substance present
INTENSIVE properties do not depend on the
amount of substance
ONE OF THESE
AND
Examples:
electrical conductivity……………………..… P, I
reactivity with water………………………..... C, I
heat content (total energy)………………..… P, E
ductile: can be drawn (pulled) into wire….. P, I
malleable: can be hammered into shape… P, I
brittle……………………………………………. P, I
magnetism……………………………………… P, I
Physical and Chemical Properties
Examples of Physical Properties
Boiling point
Color
Slipperiness
Electrical conductivity
Melting point
Taste
Odor
Dissolves in water
Shininess (luster)
Softness
Ductility
Viscosity (resistance to flow)
Volatility
Hardness
Malleability
Density (mass / volume ratio)
Examples of Chemical Properties
Burns in air
Reacts with certain acids
Decomposes when heated
Explodes
Reacts with certain metals
Reacts with certain nonmetals
Tarnishes
Reacts with water
Is toxic
Ralph A. Burns, Fundamentals of Chemistry 1999, page 23
Chemical properties can ONLY be observed during a chemical reaction!
The formation of a
compound
The formation of a
mixture
Physical & Chemical Changes
CO2
crushing
heating
Pyrex
PHYSICAL
CHANGE
Limestone,
CaCO3
CHEMICAL
CHANGE
CaO
Crushed limestone,
CaCO3
Lime and
carbon dioxide,
CaO + CO2
Sunlight
energy
O2
Pyrex
Pyrex
H2O2
H2O
Light hastens the decomposition of hydrogen peroxide, H2O2.
The dark bottle in which hydrogen peroxide is usually stored
keeps out the light, thus protecting the H2O2 from decomposition.
States of Matter
SOLID
((
((
((
((
((
))((
))((
))((
))((
))((
))((
))((
))((
))((
))((
vibrating
LIQUID
GAS
))
))
))
))
))
translating;
close together
translating quickly;
far apart
Changes in State
Energy put into system
sublimation
melting
SOLID
boiling
LIQUID
freezing
GAS
condensation
deposition
Energy removed from system
Energy
 the ability to do work
potential energy: stored energy
-- stored in bonds between atoms
e.g., in food,
gasoline,
batteries
kinetic energy: energy of motion
-- wiggling, translating,
and rotating of particles
-- “hot” gas particles move
faster, have more KE
Law of Conservation of Energy: Eafter = Ebefore
2 H2
+
+
O2


2 H 2O
+
+
energy
For the combustion of acetylene…
PEreactants
Energy is conserved.
ENERGY
heat, light, sound
KEstopper
PEproducts
C2H2 + O2
CO2 + H2O
Energy Changes
endothermic change: system absorbs heat
-- beaker feels cold
exothermic change: system releases heat
-- beaker feels hot
Choose “endo” or “exo”…
water boiling ENDO
paper burning EXO
steam condensing EXO
CO2 subliming ENDO
water freezing EXO
ice melting ENDO
Reaction Coordinate
ACTIVATION
Diagrams
ENERGY
R
P
Energy
Energy
P
exothermic
(most chemical reactions)
R
endothermic
(photosynthesis)
C + O2  CO2
CO2 + H2O + sunlight  C6H12O6 + O2
The Mole
The mole is the SI unit
for “amount of substance.”
Atoms are so small, it is impossible to count them by
the dozens, thousands, or even millions.
To count atoms, we use the concept of the mole
1 mole of
atoms = 602,000,000,000,000,000,000,000 atoms
6.02 x 1023 atoms
That is, 1 mole of atoms = _________
How Big is a Mole?
…about the size of a chipmunk,
weighing about 5 oz. (140 g), and
having a length of about 7 inches (18 cm).
I meant, “How Big is 6.02 x 1023?”
BIG.
6.02 x 1023 marbles would cover the
entire Earth (including the oceans)
…to a height of 2 miles.
6.02 x 1023 $1 bills stacked face-to-face
would stretch from the Sun to Pluto
…and back …7.5 million times.
(It takes light 9,500 years to travel that far)
For any element on the Periodic Table,
one mole of that element
(i.e., 6.02 x 1023 atoms of that element)
has a mass in grams equal to the decimal
number on the Table for that element.
1023)
1 mole of (i.e., 6.02 x
helium atoms
has a mass of 4.0 grams.
1 mol Ne = 20.2 g
1 mol Ar = 39.9 g
1 mol Kr = 83.8 g
1 mol Xe = 131.3 g
1 mol Rn = 222 g
2
He
4.003
10
Ne
20.180
18
Ar
39.948
36
Kr
83.80
54
Xe
131.29
86
Rn
(222)
Island Diagram
MASS
(g)
1 mol = molar mass (in g)
MOLE
(mol)
Particle
(atoms)
1 mol = 6.02 x 1023 particles
Island Diagram
Problems
1. How many moles is 3.79 x 1025 atoms of zinc?
3.79 x 1025 at.
1 mol
= 63.0 mol Zn
6.02 x 1023 at.
2. How many atoms is 0.68 moles of zinc?
0.68 mol.
6.02 x 1023 at.
1 mol
= 4.1 x 1023 at. Zn
3. How many grams is 5.69 moles of uranium?
5.69 mol 238.0 g
1 mol
= 1,354 g U
= 1.35 x 103 g U
4. How many grams is 2.65 x 1023 atoms of neon?
2.65 x 1023 at. 1 mol
6.02 x 1023 at.
20.2 g
1 mol
= 8.9 g Ne
5. How many atoms is 421 g of promethium?
421 g
1 mol
145 g
6.02 x 1023 at.
1 mol
= 1.75 x 1024 at. Pm