unit 1 - data analysis
TRANSCRIPT
Chapter 2
30°C 30°F
SI unit
Measuring Volume
We will be using graduated cylinders to find the volume of liquids and other objects.
Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water.
What is the volume of water in the cylinder? _____mL
What causes the meniscus?
A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.
Measuring Liquid Volume
Imag
es c
reat
ed a
t ht
tp:/
/ww
w.s
tand
ards
.dfe
s.go
v.uk
/prim
aryf
ram
ewor
k/do
wnl
oads
/SW
F/m
easu
ring_
cylin
der.
swfWhat is the volume of water in each cylinder?
Pay attention to the scales for each cylinder.
Measuring Solid Volume
10 cm
9 cm
8 cm
We can measure the volume of regular object using the formula length x width x height.
_____ X _____ X _____ = _____
http
://re
sour
ces.
edb.
gov.
hk/~
s1sc
i/R_S
1Sci
ence
/sp/
en/s
ylla
bus/
unit1
4/ne
w/te
stin
gmai
n1.h
tm
We can measure the volume of irregular object using water displacement.
Amount of H2O with object = ______
About of H2O without object = ______
Difference = Volume = ______
How hot? How cold? direction of Heat Transfer
Celsius – 0 0C Freezing Point of Water 100 0C Boiling Point of Water
Kelvin = C° + 273 No degree signs are used O Kelvin = -273.150 C
▪ coldest possible temperature
Length – size meter (m)
Mass – amount of matter Kilogram (kg) or gram (g)
Volume – space something takes up Liter (l) or centimeters cubed (cm3)
Temperature – amount of heat Kelvin (K) = celsius + 273
Measure of how much matter is squeezed into a given space
density = mass volume
A block of wood and a block of steel have the same volume
What happens to the density of an object if it is cut into pieces?
Which has the greater density, a single uranium atom or Earth?
coefficient x 10 raised to a power
Single gram of hydrogen 602,000,000,000,000,000,000,000
molecules = 6.02 x 1023 molecules
Mass of an atom of gold 0.000000000000000000000327 grams = 3.27 x 10-22 grams
36,000 3.6 x 104
503,000,000 5.03 x 108
0.00076 7.6 x 10-4
The valid digits of a number In measurement: includes all of the
digits that are known, plus a last digit that is estimated
Significant: nonzero digits final zeros after the decimal points zeros between two other significant
digits
Not significant zeros used solely for spacing the
decimal point are not significant.
each have only two sig figs 0.0071 meter 0.42 meter 0.000099 meter
7.1 x 10-3 meter4.2 x 10-1 meter9.9 x 10-5 meter
ValueValue
5.605.60
5.65.6
0.0120.012
0.00120030.0012003
0.01200.0120
0.00120.0012
# of significant # of significant figuresfigures
33
22
22
55
33
22
If the digit immediately to the right of the last significant digit is less than 5, it is dropped 5 or greater - last significant digit
increased by 1 41.58 square meters 41.6 square
meters
Round 65.145 meters to 4 sig figs 65.15m
Round 100.1°C to 1 sig fig 100°C
Round 154 cm to 2 sig figs 150
Round 0.000718 kilograms to 2 sig figs 0.00072
Counting Example: 23 people in the classroom
▪ (Not 22.9 or 23.1) 23.00000000……………….
Exactly defined quantities Example: 60 minutes = 1 hour
▪ 60.00000000……………………..
calculated answer cannot be too precise not more precise than the least precise
measurement
Multiplication and Division same number of sig figs as the measurement
with the least number of sig figs
Addition and Subtraction same number of decimal places as the
measurement with the least number of decimal places
Accuracy How close a
measurement comes to the actual value of what is being measured
Precision How close a series
of measurements are to one another
Difference between accepted value and experimental value
error = experimental value – accepted value
% error = x 100% error
accepted value
% error = x 100%
99.1°C – 100.0°C x 100% 100.0°C
0.9°C x 100% 100.0°C
0.9%
error
accepted value
=
=
=