Scientific MeasurementsScientific Measurements SI Units Significant Figures.
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Transcript of Scientific MeasurementsScientific Measurements SI Units Significant Figures.
Density and SI Units
Scientific Measurements
SI Units
Significant Figures
SI Units
Measurement system universal to scientists.
Measurement standards (base and derived)
Base unit— Quantity we can MEASURE
Derived unit-- Quantity provided by CALCULATION
SI Units (cont.)
Base
Mass = kilogram (kg)
Length = Meter (m)
Time = Second (s)
Temperature = Kelvin (°K)
Derived
Volume = m3, we will use cm3/ml ml is NOT an SI unit
Density = kg/m3, we will use g/cm3 or g/ml
Mass vs. Weight
What is the difference?
How do we measure mass?
Density
Physical property of matter/substances
Used for substance identification
Provides information on how solids/liquids interact
Ratio of a substance’s mass and volume
Density = Mass/Volume
Units = SI Unit (kg/m3), we will use g/cm3 or g/ml
Example 1: A student obtains a mass of 5.03 g for a metal and a volume of 3.24 ml?
Example 2: What is the volume of a substance with a density of 0.824 g/ml and a mass of 0.451g?
Example 3: A student records V1= 2.7ml and V2= 3.4 ml after placing an object in a
graduated cylinder. The mass of an empty beaker is 1.13g
and the mass of both the beaker and substance is
4.13g. What is the object’s density?
Density Problems
1) An object has a mass of 4 grams and a volume of 1.7 cm3. What is it’s density?
2) What is an object’s mass if it’s density is 8.3 g/cm3 and the volume is 4 cm3 ?
3) What is the volume of an object with a mass of 11 grams and a density of 4.2 g/cm3?
4) An object’s mass is found to be 40 grams. When this object is placed in a graduated cylinder with a V1 of 17ml, the V2 becomes 20 ml. What is the object’s density?
Homework
Density Problems