Transcript Measurements - Effingham County Schools

Scientific Measurements and
Conversions
August 8
Take out your notebook, label appropriately, copy and solve:
Warm-up:
How many minutes are in 6.2 hours?
How many dollars does 35 quarters equal?
Introduction to Chemistry
 SCSh4. Students will use tools and instruments for
observing, measuring, and manipulating scientific
equipment and materials.
 a. Develop and use systematic procedures for recording
and organizing information.
 b. Use technology to produce tables and graphs.
 c. Use technology to develop, test, and revise
experimental or mathematical models.
Measurements
With the person next to you, identify one object in
the room that has a measurement quantity.
Be prepared to discuss the:
• unit of measurement
• description of the measurement
• What other qualities does the object have?
Measurements
 Review
Measurements
 Derived SI Units
 Combinations of SI base units form derived units
o Example: pressure is measured in kg/m•s2, or pascals
Measurements
 Derived SI Units
 Volume is the amount of space occupied by an object
o The derived SI unit is cubic meters, m3
o The cubic centimeter, cm3, is often used
o 1 mL = 1 cm3
Measurements
 Derived SI Units
 Density is the ratio of mass to volume, or mass divided
by volume
o The derived SI unit is kilograms per cubic meter, kg/m3
o g/cm3 or g/mL are also used
o Density is a characteristic physical property of a substance
mass
m
density =
or D =
volume
V
Measurements
 Derived SI Units
 Sample Problem
o A sample of aluminum metal has a mass of 8.4 g. The
volume of the sample is 3.1 cm3. Calculate the density of
aluminum
Measurements
 Derived SI Units
 Sample Problem Answer
o Given: mass (m) = 8.4 g
volume (V) = 3.1 cm3
o Unknown: density (D)
o Solution:
mass
8.4 g
3
density =


2.
7
g
/
cm
volume
3.1 cm3
Measurements
 Dimensional analysis is a mathematical technique that
allows you to use units to solve problems involving
measurements
 Quantity sought = quantity given × conversion factor
 Example: the number of quarters in 12 dollars
number of quarters = 12 dollars × conversion factor
4 quarter
? quarters  12 dollars 
 48 quarters
1 dollar
Measurements
 Conversion Factors
 Sample Problem
o Express a mass of 5.712 grams in milligrams and in
kilograms
Measurements
 Conversion Factors
 Sample Problem Answer
o Given: 5.712 g
o Unknown: mass in mg and kg
o Solution: mg
1 g = 1000 mg
Possible conversion factors:
5.712 g 
1000 mg
1g
and
g
1000 mg
1000 mg
 5712 mg
g
Measurements
 Conversion Factors
 Sample Problem Answer
o Given: 5.712 g
o Unknown: mass in mg and kg
o Solution: kg
1 000 g = 1 kg
Possible conversion factors:
5.712 g 
1000 g
1 kg
and
kg
1000 g
1 kg
 0.005712 kg
1000 g
Mustang Challenge
SEHS is recruiting a live mascot, but wants the biggest and strongest.
Complete calculation on notes page from yesterday.
Mustang
#1: 307.82 mg
#2 : 00.0756 kg
#3 : 48.004 x 10-2 g
Which mustang weighs the most?
Scientific Measurements
Measurements
 Accuracy and Precision
 Accuracy refers to the closeness of measurements to
the correct or accepted value of the quantity measured
 Precision refers to the closeness of a set of
measurements of the same quantity made in the same
way
Scientific Measurements
August 8
Take out your homework sheet and notes from
yesterday.
Copy and Solve:
A flower grows 2.05 cm for each 50 mL of
water given. How tall will the plant grow is
given 10,000 mL of water?
Scientific Measurements
August 8
Take out your notebook, label appropriately, copy and solve:
Warm-up:
How many mL are in one Liter?
A flower requires 25 mL to grow 8 inches. If you feed the
flower 158 mL, how tall will the flower grow?
Scientific Measurements
August 9
Take out your notebook, label appropriately, copy and solve:
Warm-up:
How many hectoliters are in one kiloliter?
A flower grows 2.05 cm for each 50 mL of water given. How
tall will the plant grow is given 10,000 mL of water?
DENSITY LAB- Rm. 304
You will need:
1. One sheet of paper
2. Pencil
3. Calculator
Observe all lab safety rules
- Read and follow all directions
- Goggles
Scientific Measurements
August 10
Pass your lab to the center, make sure your name is on it
Take out your notebook, label appropriately, copy and solve:
Warm-up:
How many milliliters of water will it take to fill a 2 L bottle
that already contains 1.87 L of water?
Measurements
 Accuracy and Precision
Measurements
 Significant Figures
 Significant figures in a measurement consist of all the
digits known with certainty plus one final digit, which
is somewhat uncertain or is estimated
 The term significant does not mean certain
Measurements
 Significant Figures
 Reporting measurements
using significant figures
Measurements
 Significant Figures
 Determining the number of significant figures
Measurements
 Significant Figures
 Sample Problem
o How many significant figures are in each of the following
measurements?
a. 28.6 g
b. 3440. cm
c. 910 m
d. 0.04604 L
e. 0.0067000 kg
Measurements
 Significant Figures
 Sample Problem Solution
a. 28.6 g
There are no zeros, so all three digits are significant
b. 3440. cm
By rule 4, the zero is significant because it is immediately
followed by a decimal point; there are 4 significant figures
c. 910 m
By rule 4, the zero is not significant; there are 2 significant
figures
Measurements
 Significant Figures
 Sample Problem Solution
d. 0.04604 L
By rule 2, the first two zeros are not significant; by rule 1, the
third zero is significant; there are 4 significant figures
e. 0.006 700 0 kg
By rule 2, the first three zeros are not significant; by rule 3,
the last three zeros are significant; there are 5 significant
figures
Measurements
 Significant Figures
 Addition or subtraction with significant figures
o When adding or subtracting decimals, the answer must have
the same number of digits to the right of the decimal point as
there are in the measurement having the fewest digits to the
right of the decimal point
Measurements
 Significant Figures
 Multiplication or division with significant figures
o For multiplication or division, the answer can have no more
significant figures than are in the measurement with the
fewest number of significant figures
Measurements
 Significant Figures
 Sample Problems
o Express each answer to the correct number of significant
figures
a. 5.44 m - 2.6103 m
b. 2.4 g/mL  15.82 mL
Measurements
 Significant Figures
 Sample Problem Solutions
a. 5.44 m - 2.6103 m = 2.84 m
There should be two digits to the right of the decimal point, to
match 5.44 m
b. 2.4 g/mL  15.82 mL = 38 g
There should be two significant figures in the answer, to match
2.4 g/mL
Measurements
 Scientific Notation
 In scientific notation, numbers are written in the form
M × 10n, where the factor M is a number greater than
or equal to 1 but less than 10 and n is a whole number
o Example: 0.000 12 mm = 1.2 × 10−4 mm
o Move the decimal point four places to the right and multiply
the number by 10−4
Measurements
 Scientific Notation
 Determine M by moving the decimal point in the
original number to the left or the right so that only one
nonzero digit remains to the left of the decimal point
 Determine n by counting the number of places that you
moved the decimal point. If you moved it to the left, n
is positive. If you moved it to the right, n is negative
Measurements
 Scientific Notation
 Addition and subtraction —These operations can be
performed only if the values have the same exponent
(n factor)
o Example: 4.2 × 104 kg + 7.9 × 103 kg
4.2 × 10 4 kg
+0.79 × 10 4 kg
7.9 × 10 3 kg
or
+42 × 10 3 kg
4.99 × 10 4 kg
49.9 × 10 3 kg = 4.99 × 10 4 kg
rounded to 5.0 × 10 4 kg
rounded to 5.0 × 10 4 kg
Measurements
 Scientific Notation
 Multiplication —The M factors are multiplied, and the
exponents are added algebraically
o Example: (5.23 × 106 µm)(7.1 × 10−2 µm)
= (5.23 × 7.1)(106 +10-2)
= 37.133 × 104 µm2
= 3.7  105 µm2
Measurements
 Scientific Notation
 Division — The M factors are divided, and the
exponent of the denominator is subtracted from that of
the numerator
o Example:
5.44  107 g
8.1  104 mol
= (5.44 / 8.1)(107 -104)
= 0.6716049383 × 103
= 6.7  102 g/mol
Express the following quantities in scientific notation:
a.8 800 000 000 m
b. 0.0015 kg
c. 0.000 000 000 06 kg/m3
d. 8 002 000 Hz
e. 0.009 003 amp
f. 70 000 000 000 000 000 km
g. 6028 L
h. 0.2105 g
i.
600 005 000 kJ/h
j. 33.8 m2
Matter/ Mixtures
August 13
Take out your notebook, label appropriately, copy #2 and solve:
Warm-up:
1. A metallurgist is going to make an experimental alloy that
requires adding 325 g of bismuth to 2.500 kg of molten lead. What
is the total mass of the mixture in kilograms?
3
2
2. 2.58 x 10 cm x 3.3 x 10 cm =
Matter
Matter and Its Properties
 Matter
 Volume is the amount of three dimensional space an
object occupies
 Mass is a measure of the amount of matter
 Matter is anything that has mass and takes up space
Matter and Its Properties
 Properties of Matter
 Extensive properties depend on the amount of matter
that is present
o Volume
o Mass
o The amount of energy in a substance
Matter and Its Properties
 Properties of Matter
 Intensive properties do not depend on the amount of
matter present
o
o
o
o
o
Melting point
Boiling point
Density
Ability to conduct electricity
Ability to transfer energy as heat
Matter and Its Properties
 Physical Properties/Physical Changes
 Physical property is a characteristic that can be
observed or measured without changing the identity of
the substance
o Color, volume, hardness, temperature
o Melting point and boiling point
 Physical change is a change in a substance that does
not involve a change in the identity of the substance
o Grinding, cutting, melting, and boiling
Matter and Its Properties
 Physical Properties/Physical Changes
 Change of state is a physical change of a substance
from one state to another
o Solid state, matter has definite volume and definite shape
o Liquid state, matter has a definite volume but an indefinite
shape
o Gas state, matter has neither definite volume nor definite
shape
o Plasma is a high-temperature physical state of matter in
which atoms lose most of their electrons, particles that make
up atoms
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!
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.
Matter and Its Properties
 Physical Properties/Physical Changes
Matter and Its Properties
 Physical Properties/Physical Changes
Matter and Its Properties
 Physical Properties/Physical Changes
Matter and Its Properties
 Chemical Properties/Chemical Changes
 Chemical property relates to a substance’s ability to
undergo changes that transform it into different
substances
 Flammability, toxicity, heat of combustion
 Chemical change or chemical reaction is a change in
which one or more substances are converted into
different substances
Matter and Its Properties
 Chemical Properties/Chemical Changes
Magnesium + Oxygen = Magnesium Oxide
Iron + Oxygen/Water/Acids = Iron Oxide
Matter and Its Properties
 Chemical Properties/Chemical Changes
 Reactants are the substances that react in a chemical
change
 Products are the substances that are formed by the
chemical change
carbon + oxygen
reactants
yields
carbon dioxide
product
Matter and Its Properties
 Evidence of Chemical Change
Matter/Mixtures
August 14
Copy and Solve
1. An airplane descends at 35 mi/hr for 80 minutes. How
far did the airplane descend?
2. How many significant figures does 0.0072070 have?
3. Write the number above in scientific notation.
Calculation Quiz Tomorrow
1. 30mL = ______________ L
2. Density of an iron ore sample with a mass of 5 kg and a volume of 2.5 cm(3)
3. 37. 75 m + 3.876 m=
4. 10 power 3 x 10 power 5 =
5. A swimmer can swim at a consistent rate of 5 m per sec. How may centimeters
can the swimmer travel in 1 min?
6. 1.567 x 10(power 6) ÷ .54 x 10 (power 2)
Matter and Its Properties
 Energy and Changes in Matter
 Energy is always involved when physical or chemical
changes occur
 Energy can be in various forms
o Heat
o Light
 Energy can be absorbed or released in a change, it is
not destroyed or created
o Law of conservation of energy
Matter and Its Properties
 Classification of Matter
Matter and Its Properties
 Classification of Matter
 Mixture is a blend of two or more kinds of matter, each
of which retains its own identity and properties
o mixed together physically
o can usually be separated
 Homogeneous mixtures are called solutions
o Uniform in composition (salt-water solution)
 Heterogeneous mixtures
o Not uniform throughout (clay-water mixture)
Matter and Its Properties
 Give examples of each type of mixture:
 Homogenous:
Heterogeneous:
Matter and Its Properties
 Give examples of each type of mixture:
Matter and Its Properties
 Classification of Matter
 Pure substance has a fixed composition
 Pure substances are either compounds or elements
 A pure substance differs from a mixture in the
following ways
o Every sample of a given pure substance has exactly the same
characteristic properties and composition
o Example: Water is always 11.2% hydrogen and 88.8%
oxygen by mass
Matter and Its Properties
MIXTURE LAB
The mixture you will work with contains salt, sand, iron filings, and saw
dust. All four substances are in dry, granular form.
You are to make a plan for what you will do to separate the mixture into
the pure substances. You must write out a plan with your partners as to
how you will separate the mixture.
POSSIBLE MATERIALS
aluminum foil
cotton balls
distilled water
forceps
magnet
paper clips
paper towels
Petri dish
pipets
plastic forks
plastic spoons
plastic straws
sample of mixture and components (sand,
iron filings, salt, poppy seeds)
tissue paper
transparent tape
wooden splints
Periodic Table
August 15
Copy and Solve
3
1. 7.736 x 10 km
/
2
2.3 x 10 km
2. How many significant figures does 0.0072070 have?
3. Write the number about in scientific notation.
Calculations QUIZ
Show all work to receive full credit. Questions 1, 2, and 5 do
not require work to be shown.
When you finish, turn your quiz into the 1st period shelf.
Finish completing and reviewing the Chapter 1 and 2
vocabulary.