Chemistry !! The study of the composition, __________, and properties of matter and the...
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Transcript of Chemistry !! The study of the composition, __________, and properties of matter and the...
Chemistry !!The study of the composition,
__________, and properties of matter
and the ____________________
Chemists make measurements to ________________ of matter. To keep things consistent, we all work in __________
Matter?
Matter is anything that occupies space and has mass. Chemistry is the study of matter and how it changes
Volume - _____________
(even air !)
measured in ____and ____
Matter
Mass - measure of __________.
____in ____________
Any substance that has a definite composition
Chemical
Examples:
The smallest unit of an
Element that _____________
Properties of that element
Atom
Classification of Matter
Elements _____ be separated into simpler substances by chemical means. Example: __________ Smallest part is an ______
Elements/Compounds
Compounds are composed of atoms of _________ elements. Examples:_________________
Phases of Matter
There are three common phases of matter:
•____ – closely spaced and _____
•____ – closely spaced but _____
•____ – large separation; mostly _____________
3 States of Water
Phase Atom Movement
Shape Volume Energy
Solid
Liquid
Gas
Properties
An ________ property _______ on __________ matter is being considered. Example:
An _________ property _______ depend on __________ matter there is. Example:
Properties?
In Chemistry we study of matter and how it changes; we need to be able accurately observe properties to do this!
Properties
A __________ property is a characteristic that can be observed or measured _______ changing the identity of the substance.
Examples include
A _________ property is a characteristic that describes the _______ of a substance to undergo changes that alter its identity.
Examples include the _____ of coal ______ and the _____ of iron _______.
Properties
Properties
A _______ change is when a substance changes physical condition but ________ involve a change in composition.
A _______ change is when a substance changes a substance ______________________ of substances.
Properties
Classify each of the following as either a physical change or a chemical change:
• Tearing a sheet of paper
• Melting a piece of wax
• Burning a log
• Milk turns sour
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Mixtures contain two or more substances and generally can be __________________.
Pure substances have a _______ _____________ and distinct properties.
Mixtures/Substances
Homogeneous means the ______ throughout. ________ separate by filtering. Ex.
Mixtures
Heterogeneous means that it is ___________. ____ separate by filtering. Ex.
Scientific Method
Definitions•___________ – a testable
statement•______ – an explanation of how
phenomena occur and how data and events are related
•_________ – a broad generalization that explains a body of facts
EquipmentCommonly used for liquid
measures
Liquid Volumes
Volume read to the bottom of the _________
SI Units?
Measurements can be made in many different units. To be consistent, all scientists use the metric system to report measurements. Metric system units are called ________
_________________
SI Units ExamplesMeasureme
ntUnit Abbrev.
mass gram
length meter
volume liter
time second
temperature Kelvin
energy JouleAmount of
sampleMoles
Label each instrument with the SI correct units
Temperature Conversions
Like most measurements, temperature has many forms. There are three common ways to report temperature: Fahrenheit (F ), Celsius (C ), and Kelvin (K ).
K = C + 273 or C = K - 273
F = (1.8)(C ) + 32
Temperature Conversion?
So, if it is 35 C , would you go skiing or swimming?
What is the temperature inF ?
In K ?
____ F
____ K
SI SubunitsPrefix Abbrev. Factor
Mega M- 1 x 106
Kilo K- 1 x 103
Hecto H- 1 x 102
Deka D- 1 x 101
Base Unit – meter (m), liter (l), or grams (g)
deci- d- 1 x 10-1
centi- c- 1 x 10-2
milli m- 1 x 10-3
micro- 1 x 10-6
nano- n- 1 x 10-9
pico- p- 1 x 10-12
Metric Conversions
Meter (m)Liter (l)Gram (g)Joule (J)
Unit Conversion?In Chemistry, we can make measurements in many different units. So, we often need to convert to another set of units. We need three things:
1. where you are __________ 2. where you are _______, and 3. the __________________ to get you there.
Converting Units ExampleTo convert units you need to know
where you are starting, finishing, and the conversion factor.
Find the number of cm in 2.1 meters.
We know: 1 m = 100 cm 2.1 m 100 cm = ____ cm 1 m
Find the number of g in 8,200 g.
We know: 1000 g = 1 g
8,200 g 1 g = ____ g 1000 g
Converting Units
SI Subunits Conversions
10.5 g= _________ kg
1.57 km = _______ m
3.54 mg = __________ g
3.5 J = _________ DJ
1.2 L = _____ ml
358 cm3 = _________ m3
How many cm are in 2.8 inches.
Conversion Factor: 1 in = 2.54 cm
2.8 in = ____ cm
How many inches in 12.4 cm?
12.4 cm = ____ in
Converting Units
Unit Conversion Examples
How many ounces in 600 mls?
mls = ______ oz
First we need conversion factor !
12 oz. = 355 ml
Converting TimeHow many days are there in
52,480 minutes?
= ______ days
How many minutes are there in 2.4 months?
= ___________ minutes
Conversions with two units
If you are traveling 20 miles/hour, how many meters/seconds is this?Change one unit at a time. Note, many ways to do this.
Conversions with two units
Convert 25 miles/gallon to km/liter
Convert 10 kg/liter to g/ml
= ______ km/l
= ______ g/ml
Precision vs. Accuracy
Accuracy andPrecision
_________
_______
_______________
_________
Precision
• Refers to the closeness of a set of measurements __________
• Requires that ____________ measuring the same thing be done
• Example:– 2.22,2.23,2.21 shows good precision
Accuracy
•Refers to how close an answer ________ is to __________ or correct value
•Requires that the accepted value is ______
•Use ___________ to express accuracy
Percent Error• _________ = experimental value – accepted value
(value can be _______ or ________)
• ___________ experimental value – accepted value x
100 accepted value(absolute value)
Significant figures?
In most cases it is __________ to obtain the exact value for a measurement. We need to _____________ the significant figures - the meaningful digits in a measured or calculated quantity. The trick is _______ _____________________!
Significant Figures
Rules for determining sig. figs.:
1.All non-zero #’s are sig.
2. Zeros between non-zeros are sig. (a zero sandwich!)
3. Zeros to the left of the first non-zero # are not sig.
-> ______
-> _______
-> ______
Significant Figures Rules
4. Zeros at the end of a number and to the right of a decimal are sig. They are holding a place!
5.For #’s w/out decimals, the trailing zero may or may not be sig. We use Sci. notation on these.
-> ______
1,000,000 years – now 1,000,000.019 years ??
Which zeros are important? Use scientific notation: Could be _________ or ________ or ____________, etc.
Significant Figures
Determine the sig figs & Rule #:
• 6.002 cm
• 0.0020 m
• 10.0500 g
• 7000 kg
-> _____________
-> _____________
-> ______________
-> _______________ _________________
Scientific Notation Examples
1.Distance to Sun:
93,000,000 miles -> _______ miles
2. Vacuum pressure:
0.000000001 torr -> _______ torr
Sci. Not. w/ Calculators
Example: 4 x 1023 x 5 x 10-12 = ?Action Display
Enter “4” 4
Press “EE” 4 00
Enter “23” 4 23
Press “x“ 4 23
Enter “5” 5
Press “EE” 5 00
Enter “-12” 5 -12
Press “=“ 2 12 (2 x 1012)
Significant Figures
Rules for adding and subtracting:
•Answer cannot have more digits to the right of decimal point than the original!!
89.332
+ 1.1
90.432
____round off
Significant Figures
Rules for multiplying and dividing:
•Answer cannot have more significant figures than the original!
2.8 2 s.f.
x 4.5039 5 s.f.
12.61092
___round off
Significant Figures
Report with the correct # of sig. fig.:
• 11,254.1 g + 0.1983 g
• 66.59 L – 3.13 L
• 8.16 m x 5.1355 m
• 0.0154 kg / 88.3 ml
-> ______ g
-> _______ L
-> ____m;__ sf.
-> _________ kg/ml; ___ s.f.
Measurements?
Chemists make measurements to study the properties of matter. To keep things consistent, we all work in SI Units and use significant figures. We also make many conversions between different types of _________ ________. We also make many ________________
Derived Units
•Mathematical combinations of units
•Examples are:
Density?
Density is a common physical property that relates the mass and volume of a substance:
Density =
Units: grams/mlsor
grams/cm3
Density Example
What is the density of a substance that has a mass of 84.7 g and a volume 55.4 cm3.
Density = mass/volume
g = _____ g/cm3
cm3
g cm3 = ___ cm3
g
Density ExampleWhat is the volume of a substance that has a density of 1.73 g/cm3 and a mass of 7.75 g.Density is a conversion factor. 1.73 g = 1.00 cm3 or 1.00 cm3 = 1.73 g