Chem dimensionalysis quiz Flashcards
Measuring
comparing an unknown amount to a standard unit
All measurements have 2 parts:
Number and measurement unit
Metric system consists of 7 basic units. What are 5
Length: Meter
Mass: gram
Time: Second
Temperature (absolute): kelvin
Number of particles: mole
Kilo
(10)³
Centi
(10)²
Milli
(10)³
Nano
(10)⁹
Which is longer 5 meters or 5 centimeters
5 meters
Which is heavier in mass
A) 42 grams
B) 42 milligrams
C) 42 kilograms
D) All the same
C
Which measurement is shorter? 5 millimeters or 9 nanometers
9 nanometers
Conversion factor
The number you use to change from one unit to another
Ex: 12 inches- 1 foot
Whatever you do there will always be some _________ involved with any measurement
Uncertainty
Accuracy
How close a measurement is to the exact value
Precision
How repeatable a measurement is/how close measurements are
What’s important when reporting measurements
Integrity
Which data is precise
A) 2.15; 3.14; 4.5; 3.9; 5.0
B) 3.0; 2.5; 2.75; 3.5; 1.7
C) 4.0; 4.2; 4.44; 4.15; 4.3
C
Which data is precise and accurate (True value 3.2)
A) 2.1; 2.09; 2.15; 2.11
B) 3.19; 3.21; 3.25; 3.22
C) 3.0; 2.5; 2.75; 3.5; 1.7
B
Significant digits
Report measurements to one tenth of the smallest decimal increment
Significant digits only apply to
Measured data
How many significant digits are in 342
3
How many significant digits are in 34200
3
How many significant digits in 342.0
4
How many significant digits in 242.06
5
Density
Mass over volume
