Transcript 22 inches | 1 ft

Chemistry –
Observation –
Inference –
Law –
Theory –
A law tells
a theory is an attempt to
.
Scientific Method – a systematic and logical
way to approach problem solving

Problem/observations (collect data)

Hypothesis –

Experiment –

Conclusion –
Law of Conservation of Mass/Energy –.
Physical Change –
Chemical Change –
Signs of a Chemical Reaction
•Heat or light
• ____ is produced
•A _____ is formed
•_____ is produced or made in the
reaction
•A __________ is made
Physical or Chemical change
•Ice melting
•Cooking
•Placing metal wire in acid
•Placing Alka Seltzer in water
•Tear paper
•Boiling water
•Boil potato
Physical Properties –
Chemical Properties –
Matter –
Substance –
Element –
Compound –
Mixture –
Homogeneous –
Heterogeneous –
Classify each as an element, cmpd, homo/hetero
mix
Tap water
aluminum
air
Polluted air
store bought milk
“whole” milk
Sugar
salt
14 K gold
24 K gold
H2SO4
river water
Salt water
O.J. w/pulp
ice & water
Raw hamburger
glass of Cherry Coke
mercury
Red Kool Aid
cough medicine
maple leaf
Brass
choc. chip cookie
H2O2
Chunky peanut butter
“bubble gum” medicine
steel
can of paint
1,3,5-trinitrotoluene
Ways to Separate a Mixture
•Separation by hand
•Filtration
•Evaporation
•Centrifuge
•Chromatography
•Distillation
How would you separate a mixture of:
•Salt and water
•Salt and sand
•Water and alcohol
•Clay and water
•Different colors of ink
•Blood
Qualitative Measurement –
Quantitative Measurement
Accuracy –
Precision –
Accuracy is not the same as precision
Metric Units
Mass –
Volume –
Length –
Metric Prefixes
Prefix
Name
Meaning
K
Kilo-
1,000
H
Hecta-
100
D
Deka-
10
d
Deci-
0.1
c
Centi-
0.01
m
Milli-
0.001
Converting with metric units
K H D __ d c m
1. Place 1 under starting prefix
2.Place 2 under ending prefix
3.Draw an arrow from 1 to 2. This is the
direction to move the decimal point.
4.Count the number of places to go from 1
to 2. Be sure to count the __ space.
5.Move decimal point and rewrite number.
Make the following metric conversions
13.5 g  kg
2.75 ml  l
150 mm  cm
0.0150 m  cm
0.195 cg  mg
0.750 l  ml
2.46 mg  kg
5.79 Hl  l
7.53 km  cm
0.0432 g  mg
4150 cl  l
739 dm  m
81.8 cg  kg
418.2 m  km
Scientific Notation – a way of showing very large
or small numbers.
4.7 x 103
4.7 E 3
4.7 exp 3
4.7 x 10 x 10 x 10 = 4,700
The exponent or power tells how many places the
decimal point will be moved. If the exponent is
positive,
If the exponent is negative,
The “number out front” is only allowed to have one
nonzero digit to the left of the decimal point.
Write each of these using scientific notation
0.000325
4270
16.2
19,500,000
0.125
485
0.0417
0.0000093
Write each of these as a “regular” number
2.75 E 2
9.13 E-4
7.38 E-1
8.05 E3
7.76 E-3
5.35 E-2
1.48 E6
6.39 E1
2.34 E-2
Significant Figures (sig figs) –
Atlantic/Pacific Rule
•If a decimal point is absent, count from the
Atlantic (right) side starting with the first
nonzero digit.
•If a decimal point is present, count from the
Pacific (left) side starting with the first nonzero
digit
508.0
820
0.0490
135
1000
1000.
1000.00
0.0300
1.30 E4
0.150
Defined or exact numbers have an infinite number
of significant figures.
Rounding off numbers: 0-4 drop, 5-9 add 1
Rounding numbers in calculations
Add/subtract:
Mult./divide:
When doing calculations, you round off
when the following occurs:
•When the rules for rounding change
(going from add  divide, mult  add)
•Get to the end of the problem, and
you are giving the final answer.
Conversions that you are responsible for knowing
12 in = 1 ft; 3 ft = 1 yd; 5280 ft = 1 mile
60 sec = 1 min; 60 min = 1 hr; 24 hr = 1 day,
7 day = 1 wk; 365.25 day = 1 yr
16 oz = 1 lb; 2000 lb = 1 ton
8 oz = 1 cup; 2 cups = 1 pint; 2 pints = 1 quart
4 quarts = 1 gallon
Unit analysis/dimensional analysis/factor-label:
A method of converting from 1 set of units to
another set of units using a series of conversion
factors.
A conversion factor is
12 in = 1 ft
1 ft/12 in
Each equivalency can produce
or
12 in/1 ft
Convert 22 inches to feet
•List possible conversion factors: 12 in/1 ft
1 ft/12 in
•Set up grid with starting number and units in the
upper left side:
22 inches |
|
=
feet
•Plug in conversions so that the same units are on
the diagonal
22 inches | 1 ft
| 12 inches
= 1.8 ft
Use unit analysis:
• 5.75 min  month
• 135 km  cm
• 17.5 oz  gal
• 1.5 mile  inch
• 145 mg  hg
• 135 ml  l
• 275 yds  meter (1.00 in ≈ 2.54 cm)
• 15.8 l  gal (1.00 oz ≈ 29.5 ml)
Density – a ratio of mass and volume of an object
D = M/V
M=DxV
V = M/D
Every pure substance will have its own
characteristic density. This means that density
can help identify a substance.
Density of pure water =
When two objects with different densities are
mixed:
The object with the larger density
The object with the smaller density
A pure substance has a mass of 65.3 g and a
volume of 75.0 ml. What is the density of the
object, and what happens when it is put in water?
Mercury has a density of 13.6 g/ml. What is the
volume of 745 g of mercury?
Temperature – A measure of the average kinetic
energy of the particles in a substance.
Water boils:
Water freezes:
As the temperature goes up,
As the temperature goes down,
There is a theoretical temperature at which all
motion stops: ABSOLUTE ZERO = 0 K
= -273 oC
= -459 oF
Temperature scales
oC
K
oF
0
273
32
100
373
212
37
310.
98.6
-273
0
-459
oC
+ 273 = K
K – 273 = oC
Types of Graphs
•Pie or Circle Graph: shows % or parts
of the whole
•Bar Graph: comparing two unrelated
variables
•Line Graph: comparing two related
variables. This is the most common
type of graph used in chemistry.
Graphing
•X axis:
•Y axis:
•Title: Y vs X
or
Dependent vs Independent
•Each axis should have a label
•Each “box” on the axis has to be
•Pick “easy numbers” to label boxes.
•Y axis boxes do not have to be the same value as
the X axis boxes
•Value of Box = Range of Values/#boxes
•Data points must take up at
•All points must be on the graph.
•Usually draw a single straight line through points,
best fit line, not “dot to dot”.
•Slope = Rise/Run = ΔY/ΔX = (Y2-Y1)/(X2-X1)