Transcript Slide 1

Chapter 2: Measurement
Qualitative – (QUALITY) Descriptive analysis, no
numbers
Examples: Nail lab, chromatography lab
candle lab
Quantitative – (QUANTITY) measurement, requires
a NUMBER and a UNIT
Example:
Mass (g), Length (cm),
Volume (ml or cm3)
Precision and Accuracy
Precision- How close lab measurements of the
same item are to each other
Accuracy – How close a lab measurement is to the
true value.
Dart throwing examples:
Precise but not accurate
Accurate & Precise
Not Accurate or Precise
Metric System
10
Based on the number _______
SI
The International System of Units - _____
Metric System Increments
(symbol)
Mega
------Kilo
Hecto
Deka
Base Units
deci
centi
mili
------micro
(Value)
M
1,000,000; 1,000,000 bigger
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1000; 1000 times bigger
100; 100 times bigger
10; 10 times bigger
gram (g), meter (m), liter (l)
d
0.1; 1/10; 10 times smaller
c
0.01; 1/100; 100 times smaller
m 0.001; 1/1000; 1000 times smaller
K
H
D
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u
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0.000001; 1/1000000; 1000000 times
smaller
Metric Conversions
M - - King Henry Drinks Basically delicious chocolate milk - - u
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Examples:
50,000 mg
1) 50.0g = _______
0.002359
4) 2359ug = _________g
0.250
2) 250L = ________KL
5,000,000
5) 5ML = _________L
46.2
3) 0.0462Km = _______m
0.0087
6) 87dm = ________Km
(Worksheet and activity on the Metric System)
Instruments used for measuring
Place value
Quantity
Unit
Symbol
Length
meter
m, cm
Volume
cm3 = L x W x H
liter
Mass
Temperature
grams
Celsius
L, ml
g
Instrument
ruler
0.01cm
ruler
0.01cm
Graduated 10ml = 0.01ml
cylinder
100ml = 0.1ml
balance
C
read to
thermometer
0.01g
0.5 C
Distance
Length –
Area –
Direct measurement. (ruler)
Calculated measurement
Area = Length x width
= cm2
Example: Find the area of your desk.
L = ________; W = ________
________ x ________ = _________
(Length Experiment and Area and Volume Calculations)
Volume
Direct Measurement – Using a graduated cylinder
Used to measure liquids.
Used to measure granular solids like sugar.
Meniscus – Lowest point of the curve where you read the
volume of a liquid in a graduated cylinder
3
2
meniscus
Volume = 2.2ml
1
Calculated Volume – Using a ruler. Length x width x height
Used for regularly shaped objects: cubes, etc.
Units = meters cubed
Example: Calculate the volume of your desk top.
L = _______; W = _________; H = ________
Volume continued
Water displacement –
Used to measure irregularly shaped objects
Example:
50.5
Amount of water + object = ________ml
20.5
Amount of water before = - ________ml
Volume of object
=
________ml
30.0
Interesting Fact: 1mL = 1cm3 = 1g H2O
Density
Story of the king’s crown – was it gold or was it fake?
Problem: I have a lump of yellowish, metallic looking stuff;
how do I figure out what it is?
1. Weight it
2.
Volume
3.
Density
4.
Look it up
Mass
Water displacement
D = M/V
10.00g
100.0ml
10g/100ml = 0.1g/ml
mass
volume of an object.
Density is a ratio of the ________
to the ________
ratio
mass
Density is the __________
of the __________
to the
volume
____________of
an object.
Units for density:
g/ml
or
g/cm3
physical
property
Density is a _________________
_______________
that
does not change for any one element.
Formula for density:
Density = mass/ volume
To use the triangle cover up what
you are solving for and the formula is
what is left.
(Density worksheet and lab)
M
D V