Scientific Measurement PPT

1. NKCSD eChemistry
Scientific Measurement

2. A Standard Measurement System
• All measurements have two parts: a number and a
unit. Measurements in science are based on the
metric system and use SI units.
• The SI (or Systems International d`Unites) is the
international standard system of measurement.
• The SI allows scientists to compare data and
communicate with each other about their results.
• SI units are based on multiples of 10.
King Henry Died By Drinking Chocolate Milk
kilo-
1,000
k
hecto-
100
h
deka-
10
da
BASE
1
deci-
0.1
d
centi-
0.01
c
milli-
0.001
m
2

3. 3

4. Accuracy vs Precision
The reliability and validity of measurement
depends on its accuracy and precision.
• Accuracy is the closeness of a measured value
to the correct (or accepted) value.
• Precision is the closeness of two or more
measurements to each other.
4

5. Common Chemistry Measurements
Temperature (T)
• Temperature is a measure of the average
kinetic energy of the particles in a sample
of matter, measured in Celsius and Kelvin
using a thermometer.
– SI unit for temperature is Kelvin.
Time (t)
• Time is simply a reference point,
measured in seconds (SI unit) using a
stopwatch or a digital timer.
5

6. Common Chemistry Measurements
Mass (m)
• Mass is a measure of the amount of matter in
an object, measured in grams or kilograms
using an electronic scale.
– SI unit for mass is kilogram.
• An object’s mass is the same
regardless of where it is.
• Mass is not the same as weight (the force
exerted by mass, only present with gravity,
and measured in pounds). 6

7. Common Chemistry Measurements
Volume (V)
• Volume is a measure of the
space occupied by a sample of
matter, measured in cm3 or
mL using a graduated cylinder.
• When determining the volume
of a fluid using a graduated
cylinder, always read the level
at the bottom of the meniscus.
7

8. Common Chemistry Measurements
Volume (V)
• You can find the
volume of an irregular
object through water
displacement
(immersing it in water
and seeing how much
the water level
increases).
8

9. Common Chemistry Measurements
Volume (V)
9
7 ml 38 ml Volume of Dinosaur
0.8 ml
Volume of Hammer
4 ml

10. Common Chemistry Measurements
Density (D)
• Density is a measure of the
amount of mass in a given
volume (D = m/V), measured in
g/cm3 or g/mL.
• It is determined by first finding
the mass and the volume of the
object. Then, density is the mass
of the object divided by its
volume. 10