Chapter 1: Introduction
Classification of Matter
Matter can exist in different forms or phases:
(1) States of Matter
Chapter 1: Introduction
Classification of Matter
Chapter 1: Introduction
Classification of Matter
Defined
shape?
Solid
Liquid
Gas
Defined
volume?
Distance
between
molecules?
Compressible?
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Molecules:
atom
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Elements:
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Compounds:
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Pure Substance:
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Mixtures:
Chapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Homogeneous Mixtures
<->
Heterogeneous Mixtures
Oil on water
Air
Chapter 1: Introduction
HW: 1, 2
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Phase state?
Molecules
or atoms?
Compound?
Mixture?
- what kind?
HW: 9, 15
Chapter 1: Introduction
Homogenous or Heterogeneous Mixtures?
Vinaigrette
Mud
Granite
Coffee - a
Coffee - b
Brass
Water and flour
Chapter 1: Introduction
Chapter 1: Introduction
Mixtures can be separated
... for example by
Filtration
Chromatography
Distillation
Chapter 1: Introduction
Properties of Matter
Physical Properties & Changes
→ no change in identity or composition of substance
Chemical Properties & Changes
→ how a substance reacts to form a different substance
Chapter 1: Introduction
Properties of Matter
Burning of wood:
Melting of ice:
HW: 17, 19
Chapter 1: Introduction
Physical of Chemical Property?
Zinc (Zn):
●
silver-grey metal
●
melting point: 420oC
reacts with oxygen to form
Zinc oxide (ZnO)
●
●
density (25oC) = 7.13 g/cm3
generates hydrogen when
dissolved in sulfuric acid
●
Chapter 1: Introduction
Physical or Chemical Process?
Sugar dissolving in water.
The picture on the left represents
a) compounds in the gas phase
b) elements in the gas phase
c) molecules in the gas phase
d) a heterogeneous mixture of
elements
e) a mixture of molecules in the
liquid phase
Chapter 1: Introduction
Intensive Properties…
…are independent of the amount of substance
Extensive Properties…
…depend on the amount of substance
Boiling/melting point (bp/mp)
Mass
Volume
Density
Chapter 1: Introduction
A gold nugget (1cm x 0.5 cm x 0.7 cm) has a density of 19.3 g/cm3.
A jeweler decides to use this gold nugget to make a perfect gold
Sphere with a diameter of 0.4cm. What is the density of this sphere?
Chapter 1: Introduction
Units of Measurement: Temperature
K = OC + 273
Chapter 1: Introduction
Units of Measurement
Système International d'Unités (SI units)
Mass
Length
Time
Temperature
Amount of a substance
kilogram
meter
second
Kelvin
mole
kg
m
s
K
mol
Chapter 1: Introduction
Units of Measurement
Prefixes used in the metric system:
You ABSOLUTELY MUST know these (Table 1.5 page 14):
Giga
Mega
Kilo
Deci
Centi
Milli
Micro
Nano
Pico
Femto
G
M
K
d
c
m
µ
n
p
f
gigameter (Gm)
megameter (Mm)
kilometer (Km)
meter (m)
decimeter (dm)
centimeter (cm)
millimeter (mm)
micrometer (µm)
nanometer (nm)
picometer (pm)
femtometer (fm)
= 109 m
= 106 m
= 103 m
=1m
= 10-1 m
= 10-2 m
= 10-3 m
= 10-6 m
= 10-9 m
= 10-12m
= 10-15m
Chapter 1: Introduction
Units of Measurement: Derived Units
Volume:
1m
1m
1m
1cm
1cm
(1 m)3 = 1m3 = 1cubic meter
1cm
(1 cm)3 = 1cm3 = 1cubic centimeter = 1mL
Chapter 1: Introduction
Units of Measurement: Derived Units
mass
Density =
volume
●
Generally expressed as g/mL or g/cm3
●
Depend on temperature
HW: 24, 29
Chapter 1: Introduction
Dimensional Analysis
Converting inches into cm:
Conversion factor:
same quantity but in different units
23 . 2 in 
2 . 54 cm
 58 . 9 cm
1in
- the units to be eliminated go on opposite sides of the fraction
Converting m/min into m/s:
1.2
m
1 min
m
×
= 0.020
min
60 s
s
Conversion factor
HW: 49, 52
Chapter 1: Introduction
Dimensional Analysis
More than one conversion:
A car travels 12 km per liter of gasoline. How many many miles per gallon will it go?
=>
Convert 12 km/L into mi/gallon
=>
first, convert length units: km into mi, second, convert volume units: L into gallons
(1)
km
12
×
L
1 mi
1.61 km
or
1.61 km
1 mi
Chapter 1: Introduction
Dimensional Analysis
More than one conversion:
A car travels 12 km per liter of gasoline. How many many miles per gallon will it go?
=>
Convert 12 km/L into mi/gallon
=>
first, convert length units: km into mi, second, convert volume units: L into gallons
(1)
(2)
1 mi
mi
km
= 7.45
12
×
1.61 km
L
L
mi
7.45
×
L
1 gal
3.785 L
or
3.785 L
1 gal
Chapter 1: Introduction
Dimensional Analysis
More than one conversion:
A car travels 12 km per liter of gasoline. How many many miles per gallon will it go?
=>
Convert 12 km/L into mi/gallon
=>
first, convert length units: km into mi, second, convert volume units: L into gallons
(1)
(2)
1 mi
mi
km
= 7.45
12
×
1.61 km
L
L
mi
mi
3.785 L
=
28.198
7.45
×
gal
1 gal
L
= 28
mi
gal
Correct number
of sig. figs.
Chapter 1: Introduction
Dimensional Analysis
More than one conversion:
A car travels 12 km per liter of gasoline. How many many miles per gallon will it go?
=>
Convert 12 km/L into mi/gallon
=>
first, convert length units: km into mi, second, convert volume units: L into gallons
=>
with more PRACTICE you can combine steps (1) and (2):
1 mi
km
3.785 L
mi
12
×
×
= 28
1.61 km
1 gal
L
gal
Chapter 1: Introduction
Dimensional Analysis
Conversions involving squared and cubic units:
The volume of a container is 5.3 m3. What is the volume in cm3?
=>
Convert m3 into cm3
5.3 m3 ×
100 cm
1m
Units must match in order to cancel out!
Chapter 1: Introduction
Dimensional Analysis
Conversions involving squared and cubic units:
The volume of a container is 5.3 m3. What is the volume in cm3?
=>
Convert m3 into cm3
1003 cm3
3
5.3 m ×
=
53,00000
cm
13 m3
= 5.3 × 1000000 cm3
3
= 5.3 × 106 cm3
Units must match = cube both number AND unit !
Chapter 1: Introduction
HW: 35
Uncertainty in Measurement
Inexact Numbers
Obtained by measurement
Exact Numbers
Value is known precisely
The temperature of the asphalt
on Randall Drive today?
Mass of 1L of milk?
The number of mm in
one yd of speaker
cable ?
Chapter 1: Introduction
Uncertainty in Measurement
good accuracy
good precision
poor accuracy
good precision
poor accuracy
poor precision
good accuracy
poor precision
Accuracy: how do the measured values agree with the “true” value?
Precision: how reproducible is the measurement?
Chapter 1: Introduction
Significant Figures
Which digits count?
(a) All significant digits in a number
Zeros...
(b) ...between nonzero digits count
(c) ...in the beginning of a number never count
(d) ...in the end of a number count (compare lab manual)
0.04305
4 sig figs
0.34000
5 sig figs
1.04305
6 sig figs
45,000
2 sig figs
Chapter 1: Introduction
Significant Figures
0.04305
4 sig figs
0.34000
5 sig figs
1.04305
6 sig figs
45,000
2 sig figs
This is easiest to see when written in exponential notation:
0.04305 = 4.305 x 0.01
= 4.305 x 10-2
0.34000 = 3.4000 x 0.1
= 3.4000 x 10-1
45,000 = 4.5 x 10000
= 4.5 x 104
Chapter 1: Introduction
Significant Figures
●
Final result is only as accurate as the least accurate measurement
●
The least accurate measurement determines the number of sig. figs.
(1) Division and Multiplication:
volume = 1.32cm x 1.1cm x 3.540cm = 5.14008cm3 = 5.1cm3
Answer rounded to 2 sig. figs.
velocity = 342 m / 32 s = 10.6875 m/s = 11 m/s
Answer rounded to 2 sig. figs.
Number with fewest sig. figs. determines sig. figs. of answer
Chapter 1: Introduction
Significant Figures
●
Final result is only as accurate as the least accurate measurement
●
The least accurate measurement determines the number of sig. figs.
(2) Addition and Subtraction
+
+
-
1.234
0.124
320.13
56.1
Number with fewest decimal places
(NOT sig. Figs.) determines answer
= 265.388
= 265.4
answer rounded to 1 decimal point